Apparatus for inspection with electron beam, method for operating same, and method for manufacturing semiconductor device using former

ABSTRACT

A substrate inspection apparatus  1 - 1  (FIG.  1 ) of the present invention performs the following steps of: carrying a substrate “S” to be inspected into an inspection chamber  23 - 1  maintaining a vacuum in said inspection chamber; isolating said inspection chamber from a vibration; moving successively said substrate by means of a stage  26 - 1  with at least one degree of freedom; irradiating an electron beam having a specified width; helping said electron beam reach to a surface of said substrate via a primary electron optical system  10 - 1 ; trapping secondary electrons emitted from said substrate via a secondary electron optical system  20 - 1  and guiding it to a detecting system  35 - 1 ; forming a secondary electron image in an image processing system based on a detection signal of a secondary electron beam obtained by said detecting system; detecting a defective location in said substrate based on the secondary electron image formed by said image processing system; indicating and/or storing said defective location in said substrate by CPU  37 - 1 ; and taking said completely inspected substrate out of the inspection chamber. Thereby, the defect inspection on the substrate can be performed successively with high level of accuracy and efficiency as well as with higher throughput.

BACKGROUND OF THE INVENTION

[0001] In the field of semiconductor processes, the design rule is goinginto an age of 100 nm and the production form is on a transition from amass production with a few models representative of a DRAM into asmall-lot production with a variety of models such as a SOC (Silicon onchip). This results in an increase of a number of processes, and thus animprovement in yield for each process becomes essential, which makesmore important an inspection for a defect possibly occurring in eachprocess. The present invention relates to an apparatus to be used in theinspection of a wafer after respective processes in the semiconductorprocesses, and in particular to an inspection method and apparatus usingan electron beam and also to a device manufacturing method using thesame.

[0002] In conjunction with a high integration of semiconductor deviceand a micro-fabrication of pattern thereof, an inspection apparatus withhigher resolution and throughput has been desired. In order to inspect awafer substrate of 100 nm design rule for any defects, a resolution insize equal to or finer than 100 nm is required, and the increased numberof processes resulting from a high integration of the device has calledfor an increase in the amount of inspection, which consequently requireshigher throughput. In addition, as a multi-layer fabrication of thedevice has been progressed, the apparatus has been further required tohave a function for detecting a contact failure in a via forinterconnecting wiring between layers (i.e., an electrical defect). Inthe current trend, an inspection apparatus of optical method has beentypically used, but it is expected that an inspection apparatus using anelectron beam may soon be of mainstream, substituting for the inspectionapparatus of optical method in the viewpoint of resolution and ofinspection for contact failure. The inspection apparatus of electronbeam method, however, has a weak point in that the inspection apparatusof electron beam method is inferior to the inspection apparatus ofoptical method in view of throughput.

[0003] Accordingly, it would be desirable to develop an apparatus havinghigher resolution and throughput and being capable of detecting theelectrical defects. It is known that the resolution in the inspectionapparatus of optical method is limited to ½ of the wavelength of thelight to be used, and it is about 0.2 μm for an exemplary case of avisible light having put to practical use.

[0004] On the other hand, in the method using an electron beam,typically a scanning electron microscope (SEM method) has been put topractice, wherein the resolution thereof is 0.1 μm and the inspectiontime is 8 hours per wafer (20 cm wafer). The electron microscope methodfurther has a distinctive feature that it is able to inspect for anyelectrical defects (breaking of wire in the wirings, bad continuity, badcontinuity of via). However, the inspection speed (sometime alsoreferred to as inspection speed) thereof is very low, and so thedevelopment of an inspection apparatus with higher inspection speed hasbeen expected.

[0005] Generally, since an inspection apparatus is expensive and athroughput thereof is rather lower as compared to other processingapparatuses, therefore the inspection apparatus has been used after animportant process, for example, after the process of etching, membranedeposition, CMP (Chemical-mechanical polishing) planarization or thelike.

[0006] The inspection apparatus of scanning method using an electronbeam (SEM) will now be described. In the inspection apparatus of SEMmethod, the electron beam is contracted to be narrower (the diameter ofthis beam corresponds to the resolution thereof) and this narrowed beamis used to scan a sample so as to radiate it linearly. On the otherhand, moving a stage in the direction normal to the scanning directionallows an observation region to be irradiated by the electron beam as aplane area. The scanning width of the electron beam is typically some100 μm. Secondary electrons emitted from the sample by the irradiationof said contracted and narrowed electron beam (referred to as a primaryelectron beam) are detected by a detector (a scintillator plusphoto-multiplier (i.e., photoelectron multiplier tube) or a detector ofsemiconductor type (i.e., a PIN diode type) or the like). A coordinatefor an irradiated location and an amount of the secondary electrons(signal intensity) are combined and formed into an image, which isstored in a storage or displayed on a CRT (a cathode ray tube). Theabove description shows the principle of the SEM (scanning electronmicroscope), and defects in a semiconductor wafer (typically made of Si)in the course of process may be detected from the image obtained in thismethod. The inspection speed (corresponding to the throughput) is variedin dependence on an amount of primary electron beam (the current value),a beam diameter, and a response time of the detector. The beam diameterof 0.1 μm (which may be considered to be equivalent to the resolution),the current value of 100 nA, and the response time of the detector of100 MHz are the currently highest values, and in the case using thosevalues the inspection speed has been evaluated to be about 8 hours forone wafer having the diameter of 20 cm.

[0007] In order to improve the inspection apparatus of said SEM methodto work at much higher speed (to increase the throughput), a new methodreferred to as an image projecting method has been suggested. Accordingto this method, an observation region on a sample is irradiated in blockby a primary electron beam (i.e., no scanning but an irradiationcovering a certain area), and secondary electrons emitted from theirradiated region are formed into an image in block by a lens system ona detector (a micro-channel plate (MCP) plus fluorescent screen) as animage of electron beam. That image is used in a two-dimensional CCD(charge coupled device) or a TDI-CCD (Time Delayed Integration-CCD) toconvert the image data into an electric signal, and from this imagedata, defects in the sample wafer (the semiconductor (Si) wafer in thecourse of process) may be detected.

[0008] Accordingly, there has arisen a demand for constructing anoverall system for inspecting such as a substrate with high level ofaccuracy and efficiency by using a defect inspection apparatus of saidimage projecting method having an advantage of higher throughput. Almostno study has made clear an overall structure of such an inspectionapparatus that, for example, feeds a sample to inspection as in a cleanstate to an irradiating location in the image projecting opticalapparatus, allowing for an association with the other subsystems to bebrought in alignment with it. In addition, in such an environment wherethe diameter of a wafer subject to inspection has been made larger andlarger, there has arisen a demand that the subsystems also should becorrespondingly modified to be suitable for the wafer having a largediameter.

[0009] In the inspection system, maintaining a vacuum atmosphere withinthe chamber is one of the important terms. In an apparatus such as adefect inspection apparatus that provides an ultraprecision processing,a stage for accurately positioning a sample in the vacuum atmosphere hasbeen used, wherein in the case where said stage is required to bepositioned highly accurately, one structure has been conventionallyemployed, in which the stage is supported in non-contact manner by ahydrostatic bearing. In this case, the vacuum level in a vacuum chamberis maintained by forming in an extent of the hydrostatic bearing adifferential pumping mechanism for exhausting a high pressure gas sothat the high pressure gas supplied from the hydrostatic bearing may notbe directly exhausted into the vacuum chamber. Aiming at such a stage,specifically a stage including a combination of the hydrostatic bearingand the differential pumping mechanism has been proposed, as shown inFIGS. 29[A] and [B]. In this configuration, when the stage moves, guideplanes 6 a-7 and 7 a-7 facing to the hydrostatic bearing 9-7 move forthand back between the high pressure gas atmosphere in the hydrostaticsection and the vacuum environment within the chamber. For this period,the gas is adsorbed onto the guide plane during it being exposed to thehigh pressure gas atmosphere and the adsorbed gas is discharged once theguide plane is exposed to the vacuum environment, which will repeatedlyoccur. Owing to this, every time when the stage moves, there occurs suchan event that the vacuum level within the chamber C is deteriorated,which disadvantageously has inhibited the processing including theaforementioned exposure, inspection and process by using the chargedparticle beam from being performed stably, or otherwise the sample hasbeen contaminated.

[0010] Further, there have been such problems in the above-describedstage including a combination of the hydrostatic bearing and thedifferential pumping mechanism that because of the differential pumpingmechanism having been added, the structure has become more complicatedand the reliability as a stage has decreased in contrast with theincreased cost.

[0011] As for the electron beam apparatus of the image projecting methodby itself, since a plurality of signals from a plurality of pixels onthe sample surface can be captured all at once, therefore this method isadvantageous in the point of the pattern inspection with the highthroughput, while the method is problematic in the point that the samplemay be charged due to a plurality of pixels being exposed to theirradiation of the electron beam all at once. On the other hand, in thecase where a mark for positioning on the wafer is to be detected duringthe processes, a field of view may not necessarily be such wide thatwould be required by the image projection in the pattern inspection buta narrower field of view may be sufficient, wherein it is ratherproblematic that an insufficiently small pixel size may result in aninsufficient mark detection accuracy.

[0012] Besides, for the MCP, as a total output charge amount (screencurrent×time period) is increased over a long-time use, the MCPmultiplication factor is decreased, and therefore there has been aproblem in that a defective image contrast may change or deterioratewith the same MCP applied voltage upon picking up the defective imagessuccessively for a long period in the defect inspection apparatus.

[0013] Further, an amplification factor in the image beam current amountis determined by a voltage applied between a first MCP and a second MCPand for example, the amplification factor should be 1×10⁴ with theapplied voltage of 1.4 kV. Additionally, a voltage on the order of 3 kVis applied between the second MCP and the fluorescent screen in order toinhibit the expansion of the image beam output from the second MCP. Adetector of a conventional electron beam apparatus, in which a camerasensor and a vacuum flange have been separately formed, isdisadvantageous in that it has a longer signal line, it is susceptive tosignal latency or disturbance, and it prohibits the fast driving of thedetector, which has been factors to decrease the throughput in theinspection (a process volume per time).

[0014] Further, to perform the defect inspection by using the electronbeam, an emission current flow to an electron gun is required to becontrolled so as to keep the contrast in the picked-up image at aconstant level, and typically the emission current has been controlledby adjusting a voltage applied to the Wehnelt electrode made of suchmaterial as LaB₆ (lanthanum hexaboride) disposed downstream to theelectron gun. FIG. 15 is a graph illustrating a relationship between thevoltage (in volt) applied to the Wehnelt electrode and the emissioncurrent (in microampere) of the electron gun, and it is seen from thisgraph that if the voltage applied to the Wehnelt electrode exceeds thelevel of −300 volt, the emission current increases rapidly.

[0015] However, if the electron gun operates for a long time under thecondition that the applied voltage to the Wehnelt electrode ismaintained at a constant level, an oxide film including La and B emittedfrom the electron gun may adhere to the inside of the Wehnelt electrodeand form an insulating film thereon, which will be positively charged.This is because the electron emitted from the electron gun has anaccelerating energy as much as the applied voltage to the Wehneltelectrode, and such electrons impinging upon said insulating film maycause the insulating film to emit the secondary electrons more than theelectrons flowing into the Wehnelt electrode. As a matter of fact, therehas been a problem in that the applied voltage to the Wehnelt electrodeshifting to the positive direction causes a gradual increase in theemission current of the electron gun, which makes it difficult to holdthe constant emission current.

[0016] On the other hand, advantageously the inspection apparatus havinga function as the scanning electron microscope according to the priorart, as compared to the inspection apparatus of the image projectingmethod, has no such problem that the sample is charged but has asufficient mark detection accuracy. Individually, either of them has tosolve the following problems.

[0017] For example, if a sample wafer includes a via formed therein,then a care must be taken upon performing an evaluation procedure forthe sample wafer. This is because if a large decelerating electric fieldas well as the primary electron beam by the amount of not less than acertain value is applied between the objective lens and the wafer, adischarge occurs between the via and the objective lens, and saiddischarge may possibly cause a damage to a device pattern formed in thewafer. There are a wafer of one type that is apt to incur such adischarge and a wafer of other type that hardly incurs the discharge,wherein the wafer of either type has a different condition of inducingthe discharge (different decelerating electric field voltage value anddifferent primary electron beam amount).

[0018] Further, it has been known that an edge portion of a pattern isapt to dazzle due to a higher secondary electron emission rate. With thehigher secondary electron emission rate, the detection signal of thesecondary electron beam to be output by the detector has an increasingsignal intensity, and disadvantageously this detection signal results ina masking of a signal generated by a defect, thereby deteriorating theinspection speed.

[0019] In an apparatus for evaluating the post-process condition of awafer according to the prior art, the inspection is performed toencompass the entire area of the wafer, and therefore the wafer is movedwithin a working chamber so that an arbitrary point on the wafer surfacemay be positioned in alignment with the optical axis of the electronbeam. Accordingly, the evaluation apparatus of the conventional exampleneeds a bottom area extended in the forth and back and the left andright directions by such an amount that can accommodate the movement ofthe wafer, and inevitably the evaluation apparatus has an enlarged floorarea. This enlargement of the floor area is a counter trend toward theeffective use of the clean room, thus it is desired to make theevaluation apparatus compact.

[0020] Further, said conventional apparatus requires an inspection timeof a few hours for a single wafer (a few hours/wafer) to accomplish theinspection covering the entire surface of the wafer. On the other hand,the throughput in the wafer processing apparatus reaches toapproximately 100 wafers in 1 hour (about 100 wafers/hour), which meansthat the inspection time of the wafer is equivalent to dozen times ofthe process time. Thus, in the circumstance that there is a mismatchbetween the throughput of the evaluation apparatus and the throughput ofthe processing apparatus, it would be desirable that those throughputsare matched to each other by reducing the inspection time.

[0021] A gate oxide of the semiconductor device is apt to be madethinner year by year, and it has been believed that the thickness of thefilm may be on the order of 1 nm in the year of 2005 and 0.5 nm in theyear of 2005. In addition, the minimum line width “d” of the patternformed in the sample subject to the inspection is getting narrower, andin proportion to that, it is required to reduce the pixel size used inthe evaluation. On the other hand, in order to secure an S/N ratio ofthe signal at a certain level, it is required to obtain a certain amountof detected secondary electrons per pixel, consequently leading to thetrend of increasing the amount of the primary electron per unit area. Asa result, the gate oxide is likely to be damaged (including breakdown)as it is getting thinner, while the voltage generated between both sidesof the gate oxide increases as the dose increases, thereby the gateoxide is more apt to be damaged. In this viewpoint, it is stronglydesired that such an electron beam apparatus be provided which would notgive any damage to a thin gate oxide of a sample to be inspected.

[0022] Besides, there is a need for improving the throughput as much aspossible, and thus it is desired that a sample such as a single wafer(hereafter referred to as a sample for simplicity) may be completelyinspected or evaluated within a process time as long as that taken by aprocess prior to the inspection process. In this regard, it is alsoconceivable that the inspection time per sample may be reduced byevaluating an arbitrary small number of chips among many chips in asingle sample.

[0023] Further, there has been no study on how to inhibit an aberrationdue to forming the primary beam into a multi-beam. In specific, such amethod is strongly required that forms the multi-beam by using anoptical system which prevents an image field curvature aberration, whichis a most serious aberration among aberrations associated with theprimary beam.

[0024] In conjunction with a defect inspection apparatus described abovewhich uses the image projecting system and the multi-beam scanningmethod, it has been also suggested that an image recognition technologyshould be improved so as to achieve a fast and highly accurate defectinspection on a patter of micro-fabrication. However, the prior art hasa problem that there may be a position mismatch between an image of thesecondary electron beam obtained by irradiating the primary electronbeam onto a region to be inspected on a surface of a sample and areference image which has been prepared in advance, thereby resulting inthe deterioration in the accuracy in the defect inspection. Thisposition mismatch could be a serious problem specifically when theirradiating region of the primary electron beam is in the misalignmentwith respect to the wafer and a part of the inspected pattern falls outof the detected image of the secondary electron beam, which could not becompensated for properly by simply using the technology for optimizingthe matching region within the detected image. This problem could be acritical drawback specifically in the inspection of a pattern ofhigh-precision.

[0025] An object of the present invention is to provide an inspectionmethod and an apparatus using an electron beam which have overcome thoseaforementioned problems and can detect a defect in a sample with highlevel of throughput and accuracy, and also to provide a semiconductordevice manufacturing method using these inspection method and apparatus.

SUMMARY OF THE INVENTION

[0026] The present invention provides a substrate inspection apparatuscomprising:

[0027] a. a beam source for generating an electron beam having aspecified width;

[0028] b. a primary electron optical system for helping said electronbeam reach to a surface of a substrate subject to an inspection;

[0029] c. a secondary electron optical system for guiding secondaryelectrons emitted from said substrate to a detecting system;

[0030] d. an image processing system for forming a secondary electronimage based on a detection signal of a secondary electron beam obtainedby said detecting system;

[0031] e. a stage for holding said substrate in such a manner that saidsubstrate may be moved successively with at least one degree of freedom;

[0032] f. an inspection chamber for said substrate;

[0033] g. a substrate conveying mechanism capable of carrying saidsubstrate into said inspection chamber and taking out it therefrom;

[0034] h. an image processing analyzer capable of detecting a defectivelocation on the substrate carried into said inspection chamber based onthe secondary electron image formed by said image processing system;

[0035] i. a vibration isolating mechanism for said inspection chamber;

[0036] j. a vacuum system capable of controlling a vacuum atmosphere tobe maintained in said inspection chamber; and

[0037] k. a control system for indicating and/or storing said defectivelocation on said substrate detected by said image processing analyzer.

[0038] Further, the present invention provides a substrate inspectionmethod comprising the steps of: carrying a substrate to be inspectedinto an inspection chamber; maintaining a vacuum in said inspectionchamber; isolating said inspection chamber from a vibration;successively moving said substrate with at least one degree of freedom;irradiating an electron beam having a specified width; helping saidelectron beam reach to a surface of said substrate via a primaryelectron optical system; trapping secondary electrons emitted from saidsubstrate and guiding them to a detecting system via a secondaryelectron optical system; forming a secondary electron image in an imageprocessing system based on a detection signal of the secondary electronbeam obtained from said detecting system; detecting a defective locationon said substrate based on the secondary electron image formed by saidimage processing system; indicating and/or storing the detecteddefective location on said substrate; and taking said substrate havingbeen completely inspected out of said inspection chamber.

[0039] According to the present invention, since the defect on thesubstrate can be detected by irradiating the electron beam having thespecified width while the substrate being moved successively with atleast one degree of freedom, therefore the throughput can be improved.Further, the present invention can construct an integrated defectinspection system which allows the defect inspection to be performedsuccessively with high level of accuracy and efficiency by way of takingthe substrate into/out of the inspection chamber, maintaining the vacuumwithin the inspection chamber and isolating the inspection chamber fromthe vibration.

[0040] According to a preferred embodiment of the present invention,there is provided an alternative substrate inspection apparatuscharacterized in further comprising: a mini-environment device forinhibiting dust from adhering to the substrate by applying a purge gasflow against said substrate prior to the inspection; and at least twoloading chambers which are disposed between said mini-environment deviceand said inspection chamber and controllable to the vacuum atmosphererespectively and independently, wherein said substrate conveyingmechanism includes a loader having one conveying unit capable ofconveying said substrate between said mini-environment device and one ofsaid loading chambers and another conveying unit capable of conveyingsaid substrate between one of said loading chambers and said stage, andsaid vibration isolating mechanism includes a vibration blocking unitinterposed between said inspection chamber and said loading chambers.Thereby, the vacuum within the inspection chamber can be maintainedappropriately, and thus the adhesion of the dust to the substrate can beprevented appropriately.

[0041] According to another preferred embodiment of the presentinvention, there is provided an alternative substrate inspectionapparatus characterized in further comprising a pre-charge unit forirradiating an electron beam onto said substrate disposed in saidinspection chamber to reduce non-uniformity level in an electro staticcharge on said substrate, and a potential applying mechanism forapplying a potential to said substrate.

[0042] According to still another preferred embodiment of the presentinvention, there is provided an alternative substrate inspectionapparatus characterized in further comprising an alignment control unitfor observing a surface of said substrate and controlling an alignmentthereof in order to position said substrate in place with respect tosaid primary electron optical system, and a laser-interferometer formeasuring a coordinate of said substrate on said stage, wherein saidalignment control unit uses a pattern existing on said substrate todetermine the coordinate of a subject to be inspected.

[0043] According to still another preferred embodiment of the presentinvention, there is provided an alternative substrate inspectionapparatus characterized in that said detecting system comprises an MCPfor amplifying said secondary electron beam, a fluorescent screen forconverting said amplified secondary electron beam into an optical signaland a CCD camera or a line sensor for taking out said optical signal asan image data, wherein a voltage applied to said MCP is controlled inassociation with a change in the amplification factor of the MCP inorder to determine an optimal amount of exposure for the imagecontaining said defect. Thus, the deterioration in the image multiplyingfactor due to a long time use of the MCP can be prevented, and the imagedefect contrast can be maintained always at a certain constant level.

[0044] According to still another preferred embodiment of the presentinvention, there is provided an alternative substrate inspectionapparatus characterized in that said detecting system comprises an MCPfor amplifying said secondary electron beam, a fluorescent screen forconverting said amplified secondary electron beam into an optical signaland a CCD camera or a line sensor for taking out said optical signal asan image data, wherein an emission current of said electron beam iscontrolled in association with a change in the amplification factor ofthe MCP in order to determine an optimal amount of exposure for theimage containing said defect.

[0045] Alternatively, said voltage applied to said MCP may be determinedby referring to a current MCP applied voltage-MCP gain curve. Furtheralternatively, said MCP applied voltage or the emission current of thebeam may be controlled in association with a multiplying factor of theprojection of the electron beam or a change in a line rate of said linesensor.

[0046] According to still another preferred embodiment of the presentinvention, there is provided an alternative substrate inspectionapparatus characterized in that said detecting system is incorporatedwith a feed-through unit, said feed-through unit comprising: afeed-through section made of an electrical insulating material; at leastone electricity introduction pin fixedly attached to said feed-throughsection; and a connecting wiring for connecting said at least oneelectricity introduction pin with a functional element, wherein saidfunctional element includes a sensor, and both a pressure and a kind ofgas of an inside of said feed-through section are different from thoseof an outside thereof, respectively. In that case, the functionalelement may be arranged on an inner surface of said feed-through sectionand the functional element may include a CCD or a TDI sensor. The wiringmay be formed in a net-like configuration on the surface of saidfeed-through section. Further, a metal flange may be included therein.Preferably, the electricity introduction pin transmits a signalfrequency of not less than 10 MHz.

[0047] According to still another preferred embodiment of the presentinvention, there is provided an alternative substrate inspectionapparatus characterized in that said beam source is an electron beamsource comprising a Wehnelt electrode, wherein said apparatus furthercomprises a control section for controlling a voltage applied to saidWehnelt electrode with time so that an emission current flowing to saidelectron beam source can be maintained at a constant level. Preferably,said electron beam source may comprise an electron gun having a cathodemade of LaB₆. More preferably, a flat <100> mono-crystalline orientationhaving a diameter of not less than 100 microns may be arranged in a tipportion of said cathode.

[0048] According to still another preferred embodiment of the presentinvention, there is provided an alternative substrate inspectionapparatus characterized in that said stage is provided with anon-contact supporting mechanism by means of a hydrostatic bearing and avacuum sealing mechanism by means of a differential pumping, and adivider is arranged between a location on said substrate subject to theelectron beam irradiation and a hydrostatic bearing supporting sectionof said stage so as to reduce a conductance, so that a pressuredifference may be generated between the electron beam irradiated regionand said hydrostatic bearing supporting section. According to the stageof this embodiment, since the non-contact supporting mechanism by meansof the hydrostatic bearing is applied to the supporting mechanism of anXY stage on which the sample is loaded and also the vacuum sealingmechanism by means of the differential pumping is provided in thesurrounding of the hydrostatic bearing so as to prevent the highpressure gas to be used for said hydrostatic bearing from leaking intothe vacuum chamber, therefore the stage unit can exhibit the highlyaccurate positioning performance within the vacuum atmosphere, andfurther since even if the gas adsorbed on the surface of the slideportion of the stage is discharged when the slide portion moves from thehigh pressure gas section into the vacuum environment, the dischargedgas hardly reach to the charged particle beam irradiating location dueto the blocking by the divider formed between the charged particle beamirradiating location and the stage, therefore it is difficult toincrease the pressure at the charged particle beam irradiating location.That is, employing the above configuration can help stabilize the vacuumlevel at the charged particle beam irradiating location on the samplesurface and also drive the stage with high level of accuracy, therebyallowing the process using the charged particle beam against the sampleto be performed with high precision as well as without any contaminationon the sample surface.

[0049] More preferably, said divider may include a differential pumpingstructure integrated therein. According to this embodiment, since thedivider is provided between the hydrostatic bearing supporting sectionand the charged particle beam irradiating region and the divider isfurther equipped with the differential pumping function by arranging avacuum pumping channel inside of the divider, therefore any gasdischarged from the hydrostatic bearing supporting section hardly passesover the divider and reaches to the side of the charged particle beamirradiating region. This can help further stabilize the vacuum level atthe charged particle beam irradiating location.

[0050] Still more preferably, said divider may have a cold trapfunction. Generally, in a pressure range equal to or lower than 10⁻⁷ Pa,main components of a residual gas in vacuum atmosphere or a dischargedgas from the material surface are water molecules. Accordingly,evacuating efficiently those water molecules facilitates a high vacuumlevel to be maintained stably. Then, since if the cold trap cooled downto approximately −100° C. to −200° C. is provided on said divider, thegas generated on the side of the hydrostatic bearing can be frozen to betrapped with the cold trap, the discharged gas hardly passes through tothe side of the charged particle beam irradiating region, andaccordingly the vacuum level in said charged particle beam irradiatingregion is more easily maintained to be stable. It is obvious that saidcold trap is not only effective to the water molecules but alsoeffective to trap and remove organic gas molecules of oils or the likes,which are the negative factors against a clean vacuum.

[0051] Still further preferably, said divider may be arranged at each oftwo locations which correspond to the vicinity of the charged particlebeam irradiating location and the vicinity of the hydrostatic bearing,respectively. According to this embodiment, since the dividers forreducing the conductance are provided in two locations including thevicinity of the charged particle beam irradiating location and thevicinity of the hydrostatic bearing, the interior of the vacuum chamberis to be partitioned into three chambers comprising a charged particlebeam irradiating chamber, a hydrostatic bearing chamber, and anintermediate chamber, which communicate with each other via smallconductance. Then, the vacuum pumping system is configured so that thepressure in the charged particle beam irradiating chamber is the lowest,the intermediate chamber medium, and the hydrostatic bearing chamber thehighest. By way of this configuration, even if the pressure increaseoccurs in the hydrostatic bearing chamber by the discharged gas, becauseof the pressure in this chamber having been originally set to be higherlevel, the pressure increase in the context of the coefficient ofpressure fluctuation is still retained to be low level. Accordingly, thepressure fluctuation in the intermediate chamber can be retained at muchlower level by the divider, and accordingly the pressure fluctuation inthe charged particle beam irradiating chamber can be further reduced byanother step of the divider, so that the pressure fluctuation thereincan be reduced substantially to a non-problematic level.

[0052] Preferably, the gas supplied to the hydrostatic bearing of saidstage may be either of a dry nitrogen or a highly purified inert gas.

[0053] Preferably, at least a surface of a component of said stagefacing to the hydrostatic bearing may be provided with a surfacetreatment for reducing any gas emanated therefrom.

[0054] According to still another preferred embodiment of the presentinvention, there is provided an alternative substrate inspectionapparatus characterized in that said stage is accommodated in a housingof said inspection chamber and supported by the hydrostatic bearing in anon-contact manner, wherein said housing containing said stage isevacuated to vacuum, and the differential pumping mechanism is arrangedin a surrounding of a section irradiating the electron beam onto saidsubstrate surface, for evacuating a region on said substrate subject toan electron beam irradiation. According to this embodiment, the highpressure gas for the hydrostatic bearing leaking into the vacuum chamberis primarily exhausted via a vacuum pumping pipe coupled to the vacuumchamber. Then, by arranging the differential pumping mechanism used toevacuate the region subject to the irradiation of the charged particlebeam in the surrounding of the section for irradiating the chargedparticle beam, the pressure in the charged particle beam irradiatingregion can be reduced by a great degree as compared to the pressure inthe vacuum chamber, thus achieving stably a vacuum level, at which theprocess using the charged particle beam against the sample can beperformed with no trouble. That is, the processing by way of the chargedparticle beam can be stably applied to the sample on the stage by usingthe stage having the same configuration with the conventional stage ofthe hydrostatic bearing type used typically in the atmosphere (the stagesupported by the hydrostatic bearing with no differential pumpingmechanism).

[0055] Preferably, the gas supplied to said hydrostatic bearing of saidstage may be either of a dry nitrogen or a highly purified inert gas,wherein said dry nitrogen or said highly purified inert gas, afterhaving been exhausted from said housing containing said stage, may bepressurized and supplied again to said hydrostatic bearing. According tothis embodiment, since the main component of the residual gas within thehousing in the vacuum atmosphere should be a highly purified inert gas,therefore there is no fear that the surfaces of the components withinthe vacuum chamber consisting of the sample surface and the housingcould be contaminated with water content or oil content, and furthersince even if the inert gas molecules are adsorbed on the samplesurface, they may break way from the sample surface immediately onceexposed to the high vacuum section in the differential pumping mechanismor the charged particle beam irradiating region, therefore thisembodiment can minimize the affection on the level of vacuum in thecharged particle beam irradiating region, and thus can stabilize theprocess by way of the charged particle beam against the sample.

[0056] According to still another preferred embodiment of the presentinvention, there is provided an alternative substrate inspectionapparatus characterized in further having, in addition to an imageprojecting function comprising the steps of irradiating the electronbeam having said specified width onto the substrate and projecting thesecondary electron image onto said detecting system by means of saidsecondary electron optical system, a scanning electron microscopyfunction comprising the steps of firstly forming an electron beam to benarrower than said specified width, secondarily irradiating saidnarrower electron beam onto and scanning thereby the substrate surface,and lastly detecting the secondary electron beam emitted from saidsubstrate. Taking advantage of the profit pertaining to each of bothfunctions, that is, the image projecting function and the function fordetecting the secondary emission beam, allows a single unit of patterninspection apparatus to perform the inspection with high level ofreliability and throughput as well as the mark detection in theregistration to be executed prior to the pattern inspection also withhigh level of accuracy, by switching the function from either one ofsaid two functions to the other in dependence on the condition that thesample is apt to be charged or hardly to be charged.

[0057] Preferably, the function may be switched appropriately betweenthe image projecting function and the scanning electron microscopyfunction to each other in response to the condition of the substrateduring a single substrate being inspected. Further, preferably, on thesame substrate, a pattern of a hardly charged sample area is inspectedby using said image projecting function and a pattern of an easilycharged sample area is inspected by using said scanning electronmicroscopy function. Yet further, preferably, the scanning electronmicroscopy function is used in a mark detection for a registration in awafer processing process, and said image projecting function is used ina subsequent pattern defect inspection.

[0058] According to still another preferred embodiment of the presentinvention, there is provided an alternative substrate inspectionapparatus characterized in that said image processing system captureseach of images for a plurality of regions to be inspected which havebeen displaced one from another while being superimposed partially oneon another, and said image processing system comprises a storage meansfor storing a reference image, and a defect determination means fordetermining the defect in said substrate by comparing the images of saidplurality of regions to be inspected which have been captured by saidimage processing system with said reference image stored in said storagemeans.

[0059] According to this aspect, the image obtaining means obtainsrespective images for the plurality of regions to be inspected whichhave been displaced one from another while being superimposed partiallyone on another, and the defect determination means determines the defectin the sample by comparing the obtained images for the plurality ofregions to be inspected with the reference image which has been storedin advance. In this way, since the present invention allows a pluralityof images to be taken for the inspection regions of different positions,the inspection images not being offset a lot from the reference imagecan be selectively used in the following processes so as to prevent thedefect detecting accuracy from being deteriorated by the positionmismatching. Besides, even if the sample and the image obtaining meanshave been brought in such a physical relationship that the inspectionpattern could partially fall out of the image region to be inspected,there should be extremely higher possibility that every inspectionpattern successfully falls in some one of the regions encompassed by theimages for a plurality of regions to be inspected which have beendisplaced one from another, thus preventing any errors in the inspectionwhich otherwise would have been caused by such partial lack of thepattern.

[0060] A comparison means performs, for example, what is called thematching operation between obtained respective images for a plurality ofregions to be inspected and the reference image, and if there issubstantially no difference between at least one image of those imagesfor the plurality of regions to be inspected and the reference image, itdetermines that said sample has no defect. In contrast, if there issubstantially a difference between every one of the images for theplurality of regions to be inspected and the reference image, itdetermines that said sample has a defect, thus to carry out the defectdetection with higher accuracy.

[0061] Said beam source may radiate the electron beam onto each of saidplurality of regions to be inspected, and said detecting system maydetect the secondary electron beam emitted from each of said pluralityof regions to be inspected. This can be accomplished by an additionallyprovided deflecting means for deflecting said electron beam and therebyirradiating sequentially said electron beam onto said plurality ofregions to be inspected.

[0062] A defect in the substrate may be inspected in the course ofprocess or after having been processed by using the substrate inspectionapparatus described above.

[0063] Preferred embodiments of an electron beam apparatus of scanningtype according to the present invention accomplished in order to solvethe aforementioned problems will be described below.

[0064] According to a preferred embodiment of the present invention,there is provided an electron beam apparatus for focusing a primaryelectron beam to scan a sample and detecting a secondary electron beamfrom said sample, said apparatus having been designed so as to form adecelerating electric field between the sample and an objective lens,said apparatus comprising a detector for detecting a discharge or aprecursory phenomenon of the discharge between the sample and theobjective lens and then generating a signal, and a means for receivingsaid signal from said detector to obtain a condition for inhibiting anydischarge from occurring.

[0065] Said detector may be a PMT for detecting a light occurring at thetime of said discharge or said precursory phenomenon of the discharge,or a sample ampere meter for detecting an irregular current occurring atthe time of said discharge or said precursory phenomenon of thedischarge. Further, said means for obtaining a condition for inhibitingany discharge from occurring may be a means for receiving said signalfrom said detector and then controlling a voltage of said deceleratingelectric field or an amount of said primary electron beam so as toinhibit the discharge from occurring. It may be also possible that thedetection of said discharge or said precursory phenomenon of thedischarge is performed with respect to a part of the region in thesample that would not be used as a finished product.

[0066] According to another preferred embodiment of the presentinvention, there is provided an alternative electron beam apparatusincluding a plurality of electron optical systems arranged in parallel,each of said electron optical systems having been configured so as toform a primary electron beam into an image on a sample and to form asecondary electron beam emitted from said sample into an image on adetecting means, said apparatus comprising a low-pass filter, whereinsaid detecting means outputs a detection signal of the secondaryelectron beam to said low-pas filter. Preferably, said low-pass filtercan make a cut-off frequency variable and may change the cut-offfrequency in dependence on the sample. In addition, preferably, saidelectron beam apparatus may further comprise a lens including aplurality of electrodes made of insulating material with a metal coatingapplied selectively onto surfaces thereof. Yet preferably, saidplurality of electrodes may be made of a single insulating material.

[0067] According to another preferred embodiment of the presentinvention, there is provided an evaluation apparatus disposed in thevicinity of at least one processing unit for manufacturing asemiconductor device so as to evaluate a resultant condition of a waferafter having been processed by said processing unit, said apparatuscomprising an evaluation condition setting system for setting anevaluation condition such that the resultant condition of a single wafercan be evaluated within a processing time per wafer by the processingunit.

[0068] According to still another preferred embodiment of the presentinvention, there is provided an alternative evaluation apparatuscharacterized in further comprising an electron gun for emitting anelectron beam, a lens system having an electrostatic lens made ofinsulating material with a metal coating applied onto a surface thereofand a deflector, a secondary electron beam detecting system, and animage forming circuit, wherein an image data is formed by scanning thewafer surface and then detecting the secondary electron beam. Morepreferably, said evaluation apparatus may comprise a plurality ofelectron optical columns each including the electron gun for emittingthe electron beam, the lens system and the deflector, and the secondaryelectron beam detector, wherein the image data is formed by scanning thewafer surface with a plurality of electron beams and then detecting thesecondary electron beam.

[0069] According to still another preferred embodiment of the presentinvention, there is provided an alternative evaluation apparatus forevaluating a resultant condition of a processed semiconductor device,said apparatus comprising an evaluation condition setting system forsetting an evaluation condition such that the resultant condition of onelot can be evaluated within a processing time per lot by the processingunit, wherein said evaluation apparatus further comprises an electrongun for emitting an electron beam, a lens system having an electrostaticlens made of insulating material with a metal coating applied onto asurface thereof and a deflector, a secondary electron beam detectingsystem, and an image forming circuit, wherein an image data is formed byscanning a wafer surface and then detecting the secondary electron beam.

[0070] According to still another preferred embodiment of the presentinvention, there is provided an alternative electron beam apparatus forevaluating a sample by irradiating a primary electron beam onto a samplewhile scanning said sample with a predetermined scanning width and thendetecting secondary electrons emitted from said sample, wherein afterhaving scanned a certain region on the sample with said predeterminedscanning width, the apparatus scans another region adjacent to saidcertain region by way of a movement of a stage, wherein an amount ofsaid movement of the stage is greater than said predetermined scanningwidth, so that the sample can be evaluated for a larger region byrepeating these steps. The electron beam apparatus according to thisembodiment evaluates the sample by irradiating the primary electron beamonto the sample while scanning the sample with a predetermined scanningwidth and then detecting the secondary electrons emitted from thesample, and the apparatus, after having scanned a certain region on thesample with said predetermined scanning width, scans another regionadjacent to said certain region by way of a movement of the stage, andthus repeats these steps so as to accomplish an evaluation of the samplecovering the region wider than the scanning width. An mount of themovement of the stage may be made greater than said predeterminedscanning width. The electron beam apparatus of the present invention canevaluate the sample in the larger area than the scanning width, while anamount of the movement of the stage is set to be greater than thescanning width so that it can prevent the generation of the overlappedscanning sections even in case of a distortion or position mismatchingin the scanning.

[0071] According to still another preferred embodiment of the presentinvention, there is provided an alternative electron beam apparatus forevaluating a sample by irradiating a primary electron beam onto a samplehaving a pattern of a minimum line width “d” while scanning said samplewith a predetermined scanning width and then detecting secondaryelectrons emitted from said sample, wherein if a beam diameter of theprimary electron beam is denoted by “D”, then 0.55≦D/d≦1.0.

[0072] According to still another preferred embodiment of the presentinvention, there is provided an alternative electron beam apparatus forevaluating a sample by irradiating a primary electron beam onto a samplehaving a pattern of a minimum line width “d” while scanning said samplewith a predetermined scanning width and then detecting secondaryelectrons emitted from said sample, wherein a beam diameter of theprimary electron beam “D” is selected such that a modulation transferfunction MTF of a signal at a time when the primary electron beam hasobserved a cycle pattern having a pitch equivalent to a doubled minimumline width “d” should be 0.42≦MTF≦0.8.

[0073] According to still another preferred embodiment of the presentinvention, there is provided an alternative electron beam apparatus forevaluating a sample by irradiating a primary electron beam onto a samplehaving a gate oxide and then detecting secondary electrons emitted fromsaid sample, wherein assuming that: a time period necessary forevaluating a unit area is denoted by “t”; an amount of irradiation ordose per unit area is denoted by “C” (Coulomb/cm²); a beam current ofthe primary electron beam is denoted by “I_(p)”; and a modulationtransfer function of a signal at a time when the primary electron beamhas observed a cycle pattern having a pitch equivalent to a doubledminimum line width “d” is denoted by MTF, then the beam diameter of theprimary electron beam is selected such that 1/(C·t) or (MTF)⁴I_(p) canbe maximized.

[0074] According to an preferred embodiment of the present invention,there is provided an evaluation method using an electron beam forevaluating a sample by irradiating a primary electron beam onto a sampleand then detecting a secondary electron beam emitted from said sample bythe irradiation of the primary electron beam thereon, wherein theevaluation is performed only with respect to a small number of chipsamong a large number of chips formed in a single sample. In that case,the number of said small number of chips may be equivalent to the numberof electron optical columns for forming the electron beam used for theinspection.

[0075] Regarding to an aspect of an apparatus for conducting theevaluation method, there is provided an evaluation apparatus using anelectron beam, said apparatus being equipped with an electron beamapparatus comprising: a primary optical system for irradiating a primaryelectron beam onto a sample; a secondary optical system for deliveringsecondary electrons emitted from said sample by the irradiation of saidprimary electron beam; a detecting system for detecting the secondaryelectrons; and an electron optical column for accommodating said primaryand said secondary optical systems, in which said electron opticalcolumn has an electrostatic lens including an electrode made ofinsulating material with a coating applied onto a surface thereof, andan electrostatic deflector or an electrostatic astigmatic correctinglens. Preferably, each of said electron optical columns may form aplurality of electron beams.

[0076] For a better understanding of an effect and operation and otheradvantages of the present invention, reference should be made to thefollowing detailed description of the invention taken in conjunctionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0077]FIG. 1 is a schematic diagram of a defect inspection system usingan electron beam apparatus of the image projecting type according to afirst embodiment of the present invention;

[0078]FIG. 2 is a top view illustrating a detailed configuration of an Ex B unit used in the electron beam apparatus of FIG. 1;

[0079]FIG. 3 is a cross sectional view of the E x B unit taken along theline A-A of FIG. 2;

[0080]FIG. 4 is a flow chart illustrating a flow of a defect inspectionin the electron beam apparatus of FIG. 1;

[0081]FIG. 5 is a diagram illustrating a correlation between a totaloperating time and an MCP multiplication factor according to a thirdembodiment of the present invention;

[0082]FIG. 6 is a diagram illustrating a correlation between a voltageapplied to an MCP and an MCP multiplication factor according to thethird embodiment of the present invention;

[0083]FIG. 7 is a flow chart illustrating an operational flow in acontrol circuit for controlling a voltage to be applied to an MCPaccording to the third embodiment of the present invention;

[0084]FIG. 8 shows an inspection procedure for a wafer W according tothe third embodiment of the present invention;

[0085]FIG. 9 is a schematic plan view of a feed-through unit accordingto a fourth embodiment of the present invention;

[0086]FIG. 10 is a schematic cross sectional view of the feed-throughunit taken along the line A-A of FIG. 9;

[0087]FIG. 11 is a schematic plan view encompassing approximately aquarter of an alternative feed-through unit according to the fourthembodiment of the present invention;

[0088]FIG. 12 is a schematic cross sectional view of the feed-throughunit taken along the line B-B of FIG. 11;

[0089]FIG. 13 is a schematic longitudinal cross sectional view of adefect inspection apparatus with the feed-through unit incorporatedtherein, according to the fourth embodiment of the present invention;

[0090]FIG. 14 is a schematic diagram of a defect inspection apparatusaccording to a fifth embodiment of the present invention;

[0091]FIG. 15 is a graph illustrating a relationship between a voltageapplied to a Wehnelt electrode and an elapsed time, for controlling anemission current from an electron gun to be maintained at a constantlevel according to the fifth embodiment;

[0092]FIG. 16 is a graph indicating a relationship between an emissioncurrent from an electron gun and a voltage applied to a Wehneltelectrode in the fifth embodiment according to the prior art:

[0093]FIG. 17 is an elevation view illustrating main components of aninspection apparatus according to a sixth embodiment of the presentinvention, taken along the line A-A of FIG. 18;

[0094]FIG. 18 is a plan view illustrating main components of theinspection apparatus taken along the line B-B of FIG. 17;

[0095]FIG. 19 is a cross sectional view of a mini-environment devicetaken along the line C-C of FIG. 17;

[0096]FIG. 20 is a side elevation view of a loader housing of FIG. 17,taken along the line D-D of FIG. 18;

[0097]FIG. 21 is an enlarged view of a wafer rack, wherein [A] is a sideview and [B] is a cross sectional view taken along the line E-E of [A];

[0098]FIG. 22 shows an alternative method for supporting a main housing;

[0099]FIG. 23 shows further alternative method for supporting the mainhousing;

[0100]FIG. 24 is a schematic diagram illustrating a generalconfiguration of an electron optical unit of the inspection apparatus ofFIG. 17;

[0101]FIG. 25 shows a potential applying mechanism;

[0102]FIG. 26 is a diagram illustrating an electron beam calibrationmechanism, wherein [A] is a side elevation view and [B] is a plan view;

[0103]FIG. 27 is a schematic perspective view illustrating a waferalignment control unit;

[0104]FIG. 28 is a side elevation view illustrating an alternativeembodiment of a mechanism for loading/unloading a substrate;

[0105]FIG. 29 is a cross sectional view illustrating a vacuum chamberand an XY stage of a charged particle beam apparatus according to theprior art in a seventh embodiment of the present invention, wherein [A]is an elevation view and [B] is a side elevation view;

[0106]FIG. 30 is a diagram illustrating an intensity distribution ofelectrons emitted from an electron gun used in the XY stage of FIG. 29;

[0107]FIG. 31 is a cross sectional view illustrating a vacuum chamberand an XY stage of an example of a charged particle beam apparatusaccording to the seventh embodiment of the present invention, wherein[A] is an elevation view and [B] is a side elevation view;

[0108]FIG. 32 is a cross sectional view illustrating a vacuum chamberand an XY stage of an alternative example of a charged particle beamapparatus according to the seventh embodiment of the present invention;

[0109]FIG. 33 is a cross sectional view illustrating a vacuum chamberand an XY stage of a still alternative example of a charged particlebeam apparatus according to the seventh embodiment of the presentinvention;

[0110]FIG. 34 is a cross sectional view illustrating a vacuum chamberand an XY stage of a still alternative example of a charged particlebeam apparatus according to the seventh embodiment of the presentinvention;

[0111]FIG. 35 is a cross sectional view illustrating a vacuum chamberand an XY stage of a still alternative example of a charged particlebeam apparatus according to the seventh embodiment of the presentinvention;

[0112]FIG. 36 is a cross sectional view illustrating a vacuum chamberand an XY stage of a conventional charged particle beam apparatusemployed in an eighth embodiment of the present invention, wherein [A]is an elevation view and [B] is a side elevation view;

[0113]FIG. 37 is a perspective view illustrating a differential pumpingunit used in the XY stage of FIG. 36;

[0114]FIG. 38 is a cross sectional view illustrating a vacuum chamberand an XY stage of an example of a charged particle beam apparatusaccording to the eighth embodiment of the present invention;

[0115]FIG. 39 is a cross sectional view illustrating an example of adifferential pumping mechanism arranged in the unit shown in FIG. 38;

[0116]FIG. 40 is a diagram illustrating a circulation piping system fora gas used in the unit shown in FIG. 38;

[0117]FIG. 41 is a schematic diagram of an electron beam apparatusaccording to a ninth embodiment of the present invention;

[0118]FIG. 42 is a plan view illustrating an arrangement of devices on asingle wafer according to the ninth embodiment of the present invention;

[0119]FIG. 43 is a schematic diagram illustrating an electron beamapparatus according to a tenth embodiment of the present invention;

[0120]FIG. 44 is a waveform diagram representing a pattern on a sampleand a detection signal of a secondary electron beam from said pattern,in the tenth embodiment;

[0121]FIG. 45 is a schematic block diagram illustrating a configurationof a first example of an evaluation apparatus according to an eleventhembodiment of the present invention;

[0122]FIG. 46 is a diagram illustrating a locational relationship ofelectron optical columns for explaining a second example of anevaluation apparatus having a plurality of electron optical columnsaccording to the eleventh embodiment of the present invention;

[0123]FIG. 47 is a graph indicating a relationship among MTF, (MTF)²,I_(p), (MTF)⁴I_(p) and D/d according to a twelfth embodiment;

[0124]FIG. 48 is a block diagram illustrating a schematic configurationof an optical system in an electron beam apparatus according to thetwelfth embodiment of the present invention;

[0125]FIG. 49 is a diagram illustrating an arrangement of amulti-optical column comprising a plurality of electron optical columns,which is a variation of the electron optical column 40 in the electronbeam apparatus of FIG. 47;

[0126]FIG. 50 is a diagram illustrating a method for evaluating a sampleaccording to a thirteenth embodiment of the present invention;

[0127]FIG. 51 is a diagram illustrating a conventional method forevaluating a wafer, in the thirteenth embodiment of the presentinvention;

[0128]FIG. 52 is schematic diagram illustrating an electron beamapparatus of an evaluation apparatus according to the thirteenthembodiment of the present invention;

[0129]FIG. 53 is a diagram illustrating an electrostatic deflector madeof ceramic with a surface treatment applied thereto, an axiallysymmetric lens or an astigmatic correcting lens, wherein [A] is an endview of the electrostatic deflector or the axially symmetric lens and[B] is a cross sectional view of the axially symmetric lens;

[0130]FIG. 54 is a schematic diagram illustrating an electron opticalunit according to a fourteenth embodiment of the present invention;

[0131]FIG. 55 is a plan view illustrating a tip portion of amono-crystal LaB₆ cathode of an electron gun used in the electronoptical unit of FIG. 54;

[0132]FIG. 56 is a side elevation view of the cathode of the electrongun used in the electron optical unit of FIG. 54;

[0133]FIG. 57 is a schematic diagram illustrating a defect inspectionapparatus according to a fifteenth embodiment of the present invention;

[0134]FIG. 58 shows a plurality of images to be inspected, which may beobtained in the defect inspection apparatus of FIG. 57, in conjunctionwith a reference image;

[0135]FIG. 59 is a flow chart illustrating a flow of a main routine of awafer inspection in the defect inspection apparatus of FIG. 57;

[0136]FIG. 60 is a flow chart illustrating a detailed flow of a subroutine of a process for obtaining data for a plurality of images to beinspected (step 304S) in FIG. 59;

[0137]FIG. 61 is a flow chart illustrating a detailed flow of a subroutine of a comparing process (step 308S) in FIG. 59;

[0138]FIG. 62 is a diagram conceptually illustrating a plurality ofregions to be inspected, which have been displaced from one anotherwhile superimposed one on another on a surface of a semiconductor wafer;

[0139]FIG. 63 is a schematic diagram illustrating an electron beamapparatus of the scanning type usable as a defect inspection apparatusaccording to the fifteenth embodiment of the present invention;

[0140]FIG. 64 is a flow chart illustrating a manufacturing process ofsemiconductor devices; and

[0141]FIG. 65 is a flow chart illustrating a lithography process amongthe manufacturing process of semiconductor devices of FIG. 64.

DESCRIPTION OF THE PREFERRED EMBODIMENT (First Embodiment; a defectinspection system of image projecting type)

[0142]FIG. 1 shows a schematic general configuration of a defectinspection system using an electron beam apparatus 1-1 of imageprojecting type according to a first embodiment of the presentinvention. As shown in FIG. 1, the electron beam apparatus 1-1 comprisesa primary column 21-1, a secondary column 22-1 and an inspection chamber23-1. It is to be appreciated that on the purpose of this application,the context of the term “inspection” includes an evaluation apparatusfor evaluating a result of the inspection.

[0143] An electron gun 11-1 comprising a cathode 8-1 and an anode 9-1 isarranged in an inside of the primary column 21-1, and an primary opticalsystem 10-1 is arranged along an optical axis of an electron beam 12-1(a primary electron beam) radiated from the electron gun 11-1. Further,a stage 26 is installed in an interior of the inspection chamber 23-1and a substrate S (e.g., a wafer) as a sample is loaded on the stage 26.

[0144] The primary optical system 10-1 may use an electrostatic (orelectromagnetic) lens 25-1 of quadrupole or octopole of rotationallyasymmetric type. This lens, can cause a focusing and a divergence in theX- and the Y-axis directions respectively. Such a configurationcomprising two or three steps of these lenses to optimize respectivelens conditions allows the beam irradiation region on the sample surfaceto be formed into a rectangular or elliptical shape as desired withoutany loss of radiated electrons. In specific, in the case of theelectrostatic lenses being used, four cylindrical rods may be used. Eachtwo opposite electrodes are made to be equal in potential and reversevoltage characteristics are given thereto. It is to be noted that as asubstitute for the quadrupole lens of cylindrical shape, such a lens ofconfiguration formed by dividing a normally used circular plate with anelectrostatic deflector. In the latter case, the lens may be madecompact.

[0145] A thermal electron beam source may be used as an electron gun11-1. An electron emitting (emitter) material is LaB₆. Other materialsmay be used so far as it has a high melting point (lower vapor pressureat higher temperature) and a low work function. The emitter member withits tip portion formed into cone shape or the emitter member formed intotrapezoidal cone shape with the tip portion of the cone having been cutaway may be used. The diameter of the tip of the trapezoidal cone may beabout 100 am. Although in the other method, an electron beam source ofan electric field emission type or a thermal field emission type hasbeen used, in such a case where a relatively large area (for example,100×25 to 400×100 μm²) is irradiated with a high current (on the orderof 1 μA) as is the case of the present invention, most preferably thethermal electron source using LaB₆ may be employed. (In the SEM method,typically the thermal field emission type electron beam source is used.)It is to be appreciated that the thermal electron beam source is of sucha method in which the electron emitting member is heated to emit anelectron, while the thermal field emission type electron beam source isof such a method in which a high electric field is applied to theelectron emitting member to emit an electron and further the electronbeam emitting section is heated so as to stabilize the electronemission.

[0146] On the other hand, in an interior of the secondary column 22-1, asecondary optical system 20-1 and a detector 35-1 are arranged, whoseoptical axes are in alignment with a direction approximately normal tothe substrate S (approximately the traveling direction of a secondaryelectron beam (secondary beam) emitted from the substrate S). In thesecondary optical system 20-1, a cathode lens 28-1, a numerical aperture29-1, a second lens 31-1, an E x B separator unit (a Wien filter) 30-1,a third lens 33-1, a field aperture 32-1, a fourth lens 34-1 and adeflector 35′-1 are arranged. It is to be noted that the numericalaperture 29-1 corresponds to an aperture diaphragm, which is a thinplate made of metal (Mo or the like) having a circular aperture formedtherein. Herein, an aperture section is disposed so as to be at afocused location of the primary electron beam and also at a focal pointof the cathode lens 28-1. Accordingly, the cathode lens 28-1 and thenumerical aperture 29-1 construct a telecentric electron optical systemfor the secondary electron beam.

[0147] Further, the detector 35-1 comprises as main components: a microchannel plate (MCP) 14-1, a fluorescent screen 15-1 for converting theelectrons into the light, a vacuum window 16-1 functioning as a relaybetween the vacuum system and the external component, a fiber opticplate (FOP) 17-1 for transmitting an optical image, and a TDI-CCD 18-1comprising a large number of elements for detecting the optical image.To explain the principle of the MCP 14-1, the MCP is made of millions ofultra-thin glass capillaries which have been shaped into a thin plate,each of said capillaries having a diameter of 6 to 25 μm and a length of0.24 to 1.0 mm, in which each of those capillaries acts as anindependent secondary electron amplifier when a predetermined level ofvoltage is applied thereto, and thereby the capillaries as a whole forma unit of secondary electron amplifier. The TDI-CCD 18-1 is connected toa control unit 36-1 via a memory 34-1.

[0148] The control system for controlling generally the defectinspection system of FIG. 1 comprises mainly a control unit 36-1provided with a man-machine interface and a CPU 37-1 which controls thecontrol unit controlling the respective components while performing adefect inspection from the secondary electron image obtained by theelectron beam apparatus 1-1 based on the information entered to thecontrol unit 36-1.

[0149] The control unit 36-1 is provided with an operator control panelas the man-machine interface, though not shown, through which anoperator can give the defect inspection system a variety ofinstructions/commands (for example, an entry of recipe, an instructionto start an inspection, a switching between an automatic inspection modeand a manual inspection mode, an input of all of the commands requiredin the manual inspection mode and so fourth). Further, the control unit36-1 is interconnected with a display 24-1 by means of a liquid crystal,a CRT or the likes, so as to display a confirmative image for a varietyof instructions, an information from the CPU 37-1, and the secondaryelectron image stored in the memory 34-1.

[0150] In the CPU 37-1, sending and receiving operations of a feedbacksignal to/from the electron optical system and sending and receivingoperations of a signal to/from the stage are performed respectively viaa primary and a secondary column control units 38-1, 39-1, and a stagecontroller of a stage driving mechanism 40-1, though not shown.

[0151] The primary and the secondary column control units 38-1, 39-1 aremainly in charge of a control of the electron beam optical system (thecontrol of a high precision power supply used for the electron gun, thelens, the aligner, and the Wien filter). In specific, these controlunits performs, for example, such a control (a cooperative control)operation as an automatic voltage setting for respective lens systemsand the aligner in response to respective operation modes, so that aconstant electron current may be regularly radiated onto the irradiationregion even if the magnification is changed, and the voltage to beapplied to respective lens systems, the aligner or the like may beautomatically set in response to the magnification.

[0152] The stage controller is mainly in charge of a control for amovement of the stage to allow a precise movement in the X- and theY-directions on the order of μm (with tolerance of about +/−0.5 μm).Further, in the present stage, a control in the rotational direction (θcontrol) is also performed with a tolerance equal to or less than about+/−0.3 seconds.

[0153] In addition, the CPU 37-1 also performs such functions as; acontrol of an conveying controller of a conveying mechanism 41-1, thoughnot shown, a communication with a host computer in a plant, a control ofa vacuum pumping system, a conveying of sample such as wafer, a controlof position alignment, a transmission of commands to other controllingcontrollers or the stage controller, and a receipt of information or thelike. Further, the CPU 37-1 is also in charge of such functions as: anacquisition of an image signal from an optical microscope; a stagevibration compensating function for compensating for possibledeterioration in image by feeding back a fluctuating signal of the stageto the electron optical system; and an automatic focal pointcompensating function for detecting a displacement of a sampleobservation point in the Z direction (the direction along the opticalaxis of the secondary optical system) and feeding it back to theelectron optical system so as to automatically compensate for the focalpoint.

[0154] The primary column 21-1, the secondary column 22-1 and theinspection chamber 23-1 are in communication with a vacuum pumpingsystem (not shown). The vacuum pumping system is composed of a vacuumpump, a vacuum valve, a vacuum gauge, a vacuum pipe and the like, andexhausts to vacuum an electron optical system, a detector section, asample chamber, a load-lock chamber and the like according to apredetermined sequence. In each of those sections, the vacuum valve iscontrolled so as to accomplish a required vacuum level. The vacuum levelis regularly monitored, and in the case of irregularity, an interlockmechanism executes an emergency control such as an interception ofcommunication between the chambers or between the chamber and theexhausting system by an isolation valve to secure the required vacuumlevel in the respective sections. As for the vacuum pump, a turbo pumpmay be used for main exhaust, and a dry pump of Root type may be used asa roughing vacuum pump. A pressure at an inspection spot (an electronbeam irradiating section) is practically in a range of 10⁻³ to 10⁻⁵ Pa,preferably in a range of 10⁻⁴ to 10⁻⁶ Pa as shifted by one digit down.

[0155] (Cleaner)

[0156] Since, as the electron beam apparatus 1-1 is operated, a targetsubstance is made to float by a proximity interaction (charging ofparticles in the proximity of a surface) and attracted to a high-voltageregion, therefore an organic substance would be deposited on a varietyof electrodes used for forming or deflecting an electron beam. Since theinsulating material gradually depositing on the surface of theelectrodes by the electrostatic charge affects reversely on the formingor deflecting mechanism for the electron beam, accordingly thosedeposited insulating material must be removed periodically. To removethe insulating material periodically, an electrode adjacent to theregion where the insulating material has been deposited is used togenerate a plasma of hydrogen, oxygen, fluorine or a compound includingthose elements, such as HF, O₂, NH₃, H₂O, C_(M)F_(N) or the like in thevacuum environment and to control the plasma potential in the space tobe a potential level (several kV, for example, 20 V-5 kV) where thespatter would be generated on the electrode surface, thereby allowingonly the organic substance to be oxidized, hydrogenated or fluorinatedand thereby removed.

[0157] (E x B unit)

[0158] A detailed structure of said E x B unit 30-1 (Wien filter) willbe described in detail with reference to FIG. 2 and FIG. 3 which is across sectional view taken along the line A-A of FIG. 2.

[0159] The E x B unit 30-1 is a unit of electromagnetic prism opticalsystem, in which an electrode and a magnetic pole are arranged in thedirections orthogonal to each other so that an electric field and amagnetic field are crossed at a right angle. If the electromagneticfield is selectively applied appropriately, such a condition (a Wiencondition) can be made where an electron beam entering into the fieldfrom one direction is deflected, while in the electron beam enteringfrom the opposite direction, a force applied by the electric field andanother force applied by the magnetic field are offset to each other,and thereby the primary electron beam is deflected to be radiated ontothe wafer at a right angle and the secondary electron beam is allowed tobe advanced approximately straight ahead toward the detector.

[0160] As shown in FIG. 2, a field in the E x B unit 30-1 is made tohave such as structure where an electric field is crossed with amagnetic field at a right angel in a plane normal to the optical axis,namely, an E x B structure.

[0161] In this regard, the electric field may be generated by electrodes50 a-1 and 50 b-1, each having a curved surface of concave shape. Theelectric fields generated by the electrodes 50 a-1 and 50 b-1 arerespectively controlled by control sections 53 a-1 and 53 b-1. On theother hand, by arranging the electromagnetic coils 51 a-1 and 51 b-1 soas to be crossed at a right angel with the electrodes 50 a-1 and 50 b-1for generating the electric field, the magnetic field is generated. Itis to be noted that those electrodes 50 a-1 and 50 b-i for generatingthe electric field are arranged to be point-symmetrical (may also bearranged on concentric circles).

[0162] In this case, in order to improve a uniformity of the magneticfield, a magnetic path is formed with a pole piece in a form of parallelplate shape. A behavior of the electron beam on the longitudinal crosssectional plane taken along the A-A line is shown in FIG. 3. The emittedelectron beams 61 a-i and 61 b-1, after having been deflected by theelectric field generated by the electrodes 50 a-1 and 50 b-1 and themagnetic field generated by the electromagnetic coils 51 a-1 and 51 b-1,enter onto the sample surface in the vertical direction.

[0163] In this configuration, the positions and the angles of incidenceof the irradiation electron beams 61 a-i and 61 b-1 to the electron beamdeflecting section are unconditionally determined as the energy of theelectron is determined. In addition, in order to advance the secondaryelectrons 62 a-1 and 62 b-1 straight ahead, the respective controlsections 53 a-1 and 53 b-1, and 54 a-1 and 54 b-1 control the electricfield generated by the electrodes 50 a-1 and 50 b-i and the magneticfield generated by the electromagnetic coils 51 a-1 and 51 b-1 so thatthe condition for the electric field and the magnetic field may be shownas vB=E (i.e., evB=eB; e is the electric charge (C)), and thereby thesecondary electrons is allowed to go straight through the electron beamdeflecting section 27 into the detecting system. Where, V is a velocityof the electron 32 (m/s), B is the magnetic field (T), and E is theelectric field (V/m).

[0164] An operation of the electron beam apparatus 1-1 according to thepresent embodiment will now be described in conjunction with FIG. 1.

[0165] In the electron beam apparatus 1-1, an observation region on asample is irradiated in block by a primary electron beam (i.e., noscanning but an irradiation covering a certain area), and secondaryelectrons emitted from the irradiated region are formed into an image inblock by a lens system on a detector (a micro-channel plate plusfluorescent screen) as an image of the electron beam.

[0166] (Primary electron beam)

[0167] The primary electron beam from the electron gun 11-1 (in aexample, Lab₆ may be used for a chip of the electron gun, which allowsto take out a high current with a rectangular negative electrode) entersthe Wien filter 30-1 after having been subject to a lens effect (shapingand image forming) by the primary optical system 10-1, where the beam issubject to the deflecting effect from said Wien filter 30-1 so that anorbit thereof is deflected. In the Wien filter 30-1, the magnetic fieldis crossed with the electric field at a right angle, and only thecharged particles satisfying the Wien condition of E=vB are allowed tobe advanced straight forward but the orbits of the other chargedparticles are deflected, where the electric field is E, the magneticfield B, and the velocity of the charged particle v. A force FB by themagnetic field and another force FE by the electric field may haveeffect in the same direction on the primary beam, and consequently thebeam orbit is deflected. On the other hand, the force FB and the forceFE may have effect in the opposite directions on the secondary beam andthose forces are offset to each other, so that the secondary beam isallowed to directly go straight forward.

[0168] A lens voltage of the primary optical system 10-1 has beendetermined beforehand such that the primary beam is formed into an imageat an aperture portion of the numerical aperture 29-1. That numericalaperture 29-1 prevents any excess electron beams to be dispersed in theapparatus from reaching to the sample surface and thus prevents acharge-up or a contamination in the sample S. Further, since thenumerical aperture 29-1 and the cathode lens 28-1 together form thetelecentric electron optical system for the secondary beam but not forthe primary beam, therefore the primary beams that has passed throughthe cathode lens 28-1 may turn to be slightly-diffusing beams which areradiated uniformly and similarly onto the sample S. That is to say, thisuniform irradiation accomplishes, what is called in an opticalmicroscope, the Koehler illumination.

[0169] (Secondary electron beam)

[0170] When the primary beam is radiated onto the sample, secondaryelectrons, reflected electrons or back-scattering electrons aregenerated as the secondary beam from the beam irradiated surface of thesample. The secondary beam passes through the cathode lens 28-1 whilebeing subject to a lens effect from the cathode lens 28-1.

[0171] It is to be noted that the cathode lens 28-1 is composed of threepieces of electrodes. Among those electrodes, one at the lowest positionis designed to form a positive electric field between the potentials inthe sample S side and in itself, and to intake electrons (particularly,secondary electrons with smaller directivities) so that the electronsmay be efficiently introduced into the lens.

[0172] Further, the lens effect takes place in such a way that voltagesare applied to the first and the second electrodes of the cathode lens28-1 and the third electrode is made to zero potential. Accordingly, aparallel beam of an electron beam emitted from a location other than thecenter in the field of view (out of the axis) may pass through thenumerical aperture 29-1 at the central location thereof without beingkicked out any further.

[0173] It is to be appreciated that the numerical aperture 29-1 servesto reduce lens aberrations of the second lens 31-1 to the fourth lens34-1 for the secondary beams. Those secondary beams having passedthrough the numerical aperture 29-1 may not affected by the deflectingeffect from the Wien filter 30-1 but may keep on going straight forwardthrough the filter. It is to be appreciated that although the secondarybeam includes secondary electrons, reflected electrons andback-scattering electrons, in this case, the explanation is specificallygiven to the secondary electrons which has been selected among them.

[0174] If the secondary beam is formed into an image only by the cathodelens 28-1, a magnification chromatic aberration and a distortionaberration may become too great. To solve this problem, the cathode lens28-1 is used in the combination with the second lens 31-1 to performonce an image formation. The secondary beam can be formed into anintermediate image on the Wien filter 30-1 by means of the cathode lens28-1 in conjunction with the second lens 31-1. In that case, sincetypically the magnification required to the secondary optical system hasbeen often insufficient, the third lens 33-1 and the fourth lens 34-1are added to the configuration as the lenses for magnifying theintermediate image. The secondary beam is magnified and formed into animage by the third lens 33-1 and the fourth lens 34-1 respectively,which means that the secondary beam is formed into an image two times inthis case. It is to be noted that the beam may be formed into an imageonly once by using both of the third lens 33-1 and the fourth lens 34-1(totally one time).

[0175] In addition, each of those lenses from the second lens 31-1 tothe fourth lens 34-1 should be a lens of rotationally symmetrical typeof such kind referred to as a uni-potential lens or Einzell lens. Eachlens is composed of three pieces of electrodes, in which typically outertwo electrodes have zero potentials and a voltage applied to a centralelectrode is used to causes a lens effect for controlling. Further, thefield aperture 32-1 is disposed in the intermediate image forming point.The field aperture 32-1, which constrains the field of view to belimited to a required range as similar to a field stop in an opticalmicroscope, for the case of an electron beam, blocks any excess beamsfrom entering to the fourth lens 34-1 of the subsequent step so as toprevent the charge-up and/or the contamination of the detector 35-1. Itis to be noted that the magnification can be controlled by varying thelens conditions (the focal distances) of the third and the fourth lenses33-1 and 34-1.

[0176] The secondary beam is magnified and projected by the secondaryoptical system, and then the beam, after having been doubled by themicro channel plate (MCP) 14-1, impinges upon the fluorescent screen15-1 and is converted into an image of light. The image which has beenconverted into the light passes through the vacuum window 16-1 and thefiber optic plate (FOP) 171-1 disposed in the atmosphere and isprojected on the TDI-CCD 18-1 on one to one basis. The detected imagesignal is converted into an electric signal, which will be stored in thememory 34-1 temporarily.

[0177] The control unit 36-1 reads out the image signal of the sample Sfrom the memory 34-1 and transmits it to the CPU 37-1. At that time, theimage data may be output onto the display 24-1. The CPU 37-1 performs adefect inspection of the pattern on the substrate S by way of thetemplate matching, the die-to-die intercomparison and so fourth from theimage signal.

[0178] While obtaining the secondary electron image, the CPU 37-1 readsa position of the stage 26-1 and outputs a drive control signal to thestage driving mechanism 40-1 to drive the stage 26-1, allowing for asequential detection and inspection of the images. In the case where theCCD is used as the detecting element, the moving direction of the stage26-1 extends along the shorter axis (may be along the longer axis), andthe movement is made by the step and repeat manner. As for the stagemovement in the case where the TDI-CCD is used as the detecting element,the stage is continuously moved in the accumulation direction. Since theTDI-CCD allows the image to be serially obtained, similarly to thisembodiment, the TDI-CCD may be used when the defect inspections are tobe continuously carried out. The resolution is determined depending onthe magnification and the accuracy of an image-forming optical system (asecondary optical system), and in the present embodiment, the resolutionof 0.05 μm has been obtained. In this example, with the resolution of0.1 μm and the electron beam irradiation condition of 1.6 μA for thearea of 200 μm×50 μm, the inspection time of about one hour per wafer of20 cm has been accomplished, which is 8 times as high as that in the SEMmethod. The specification of the TDI-CCD employed has, for example, 2048pixels×512 arrays with the line rate of 3.3 μs (at line frequency of 300kHz). Although the irradiation area in this example has been determinedaccording to the specification of the TDI-CCD 18-1, the irradiation areamay be changed depending on the object to be irradiated.

[0179] Thus, in the inspection apparatus 1-1 according to the presentembodiment, since the light source image is formed in the numericalaperture 29-1 and the FA opening is formed into an image on the samplesurface, therefore as to the primary beam, the beam may be radiateduniformly onto the sample. That is, this facilitates to accomplish theKoehler illumination.

[0180] Further, as to the secondary beam, since all of the principlebeams from the sample S enter the cathode lens 28-1 at a right angle(parallel to the optical axis of the lens) and pass through thenumerical aperture 29-1, therefore the peripheral light would not bekicked out, thus preventing deterioration of the image brightness in theperiphery of the sample. In addition, although a variation of the energypertained to the electron gives a different focal position, which causeswhat is called a magnification chromatic aberration (specially, for thesecondary electrons, since the energies thereof are varied to a greatextent, the magnification chromatic aberration is rather great), the useof two lenses consisting of the cathode lens 28-1 and the second lens31-1 for the image formation makes it possible to control themagnification chromatic aberration to be lower.

[0181] On the other hand, since a change of the magnification factor isexecuted after the beam having passed through the numerical aperture29-1, any changes in the determined magnification factor in the lenscondition for the third and the fourth lenses 33-1 and 34-1 still canbring an uniform image over the field of view to be obtained in thedetection side. It should be appreciated that although an even anduniform image can be obtained in the present embodiment, typicallyincreasing the magnification factor may problematically cause adeterioration in brightness of the image. Accordingly, in order toimprove this problematic condition, when the lens condition for thesecondary optical system is changed to vary the magnification factor,the lens condition for the primary optical system should be controlledsuch that the effective field of view on the sample determined inassociation with the magnification factor and the electron beam to beradiated on the sample may be equally sized.

[0182] That means, as the magnification factor is increased,consequently the field of view gets narrower, but when the irradiationenergy density of the electron beam is increased at the same time, thecurrent density of the detected electron can be kept always in aconstant level and the brightness of the image may be prevented frombeing deteriorated even if the beam is magnified and projected in thesecondary optical system.

[0183] Further, although in the inspection apparatus according to thepresent embodiment, the Wien filter has been employed, which deflects anorbit of the primary beam but allows the secondary beam to go straightforward, the application is not limited to this but the apparatus mayemploy the Wien filter with another configuration in which the orbit ofthe primary beam is deflected at an angle of, for example, 15 degreesand the orbit of the secondary beam is deflected also. In that specificcase, most preferably the secondary beam should be deflected at theangle of 5 degrees. Still further, although in the present embodiment, arectangular negative electrode and a quadrupole lens are used to form arectangular beam, the application is not limited to this but, forexample, a circular beam or an elliptical beam may be formed from acircular negative electrode, or the circular beam may be passed througha slit to extract the rectangular beam.

[0184] Alternatively, a plurality of beams may be used for scanning soas to radiate uniformly the entire region to be irradiated. In thiscase, each of those beams should be adapted to arbitrarily scan a regionassigned to respective beam (but in a manner to bring the uniformity ina total irradiation).

[0185] (Inspection procedure)

[0186] An inspection procedure for the substrate S by using the defectinspection system of FIG. 1 will now be described.

[0187] Generally, since an inspection apparatus using an electron beamis expensive and the throughput thereof is rather lower than thatprovided by other processing apparatuses, this type of inspectionapparatus is currently applied to a wafer after an important process(for example, etching, membrane deposition, or CMP (chemical-mechanicalpolishing) planarization process) to which it is considered that theinspection is required most.

[0188] A substrate S (wafer) to be inspected is, after having beenconveyed into the inspection chamber 23-1 through a conveying mechanism41-1, said inspection chamber being held in a vacuum environment by avacuum system, and having been positioned on an ultra-precise stage26-1, secured by an electrostatic chucking mechanism or the like, andthen a detect inspection is conducted according to a procedure as shownin FIG. 4 (a flow of inspection), as will be described below. It is tobe appreciated that during the inspection a vibration isolatingmechanism (not shown) should be preferably used to isolate theinspection chamber from the vibration.

[0189] At first, if required, a position of each of dies is checkedand/or a height of each location is sensed by using an opticalmicroscope (not shown), and those values are stored. Adding to those,the optical microscope may be used to obtain an optical microscope imagein an area of interest possibly including defects or the like, which mayalso be used in, for example, the comparison with an electron beamimage. Then, recipe information corresponding to the kind of the wafer(for example, after which process the inspection should be applied; whatis the wafer size, 20 cm or 30 cm, and so on) is entered into theapparatus, and subsequently, after a designation of an inspection place,a setting of an electron optical system and a setting of an inspectioncondition being established, a defect inspection is conducted accordingto the operation of the aforementioned electron beam apparatus 1-1typically at real time while simultaneously obtaining the image. A fastdata processing system with an algorithm installed therein executes aninspection, such as the comparisons between cells, between dies or thelike, and any results would be output to the display 24-1 or the likeand stored in the memory 34-1, if desired. Those defects include aparticle defect, an irregular shape (a pattern defect) and an electricdefect (a broken wire or via, a bad continuity or the like), and thefast data processing system also can automatically and at real-timedistinguish and categorize them according to a defect size, or whethertheir being a killer defect (a critical defect or the like whichdisables a chip). The detection of the electric defect may beaccomplished by detecting an irregular contrast. For example, since alocation having a bad continuity would generally be charged intopositive by an electron beam irradiation (about 500 eV) and thereby itscontrast would be decreased, the location of bad continuity can bedistinguished from normal locations. The electron beam irradiation meansin that case typically designates an electron beam source (e.g., meansfor generating thermal electron, UV/photoelectron) with lower potentialenergy arranged separately in order to emphasize the contrast by apotential difference, in addition to the electron beam irradiation meansused for a regular inspection. Before the electron beam being radiatedonto the objective region for inspection, the electron beam having thelower potential is generated and radiated. Further, the defect may beinspected based on the difference in contrast (which is caused by thedifference in flowability of elements depending on the forward orbackward direction) created by, for example, applying a positive ornegative potential relative to a reference potential to a sample such asa wafer or the like. This electron beam source may be applicable to aline-width measuring apparatus and also to an alignment accuracymeasurement.

[0190] After the inspection for the substrate S has been completed, thesubstrate S will be taken out of the inspection chamber 23-1 by means ofthe conveying mechanism 41-1.

(Second Embodiment)

[0191] A pattern inspection apparatus according to a second embodimenthas a combination of two functions including a function for imageprojecting and a function as a scanning electron microscope (i.e., afunction for detecting a secondary emission beam generated by scanningwith a primary electron beam), in which each of these two functions canbe easily switched to each other simply by an electrical operation, aswill be described later.

[0192] The pattern inspection apparatus according to the secondembodiment can be accomplished by employing the configuration of theelectron beam apparatus 1-1 shown in FIG. 1, and further adding theretothe function as the scanning electron microscope.

[0193] The function for the image projecting is mainly used in a patterninspection for a hardly-charged sample, while the function as thescanning electron microscope is mainly used in a pattern inspection foran easily-charged sample or in a mark detection in a registration to bepreformed prior to the pattern inspection. In this regard, theeasily-charged sample material includes, for example, a wafer having asilicon oxide or silicon nitride deposited on a surface thereof, whilethe hardly-charged sample material includes bare silicon, aluminumcoated silicon and so on. Further, whether a sample is easily charged orhardly charged is determined according to the following criterion. Thatis to say, it is determined based on how many percents of the surfacearea of the silicon wafer is covered with an insulating material orwhether the sample has a conductive film isolated in a island shape orconductive films continued to each other.

[0194] The detailed description of the function for the image projectionwill be omitted since it has been made in conjunction with the firstembodiment. It is to be appreciated that in the case where the presentembodiment has been applied to the image projecting function, forexample, an irradiation region of an electron beam that is formed intoan image in a reduced scale on the sample S (e.g., wafer) by theelectrostatic objective lens 28-1 may be 250 micron square, and asecondary electron beam may be magnified by the secondary optical system20-1 in a magnification factor of 300 and then enters the MCP 14-1.

[0195] The function as the scanning electron microscope will now bedescribed with reference to FIG. 1. In the pattern inspection apparatusof the second embodiment, a scanning deflector 19-1 capable ofdeflecting the primary electron beam is arranged in a step subsequent tothe electrostatic (or electromagnetic) lens 25-1 in the primary opticalsystem 10-1.

[0196] The electron beam 12-1 emitted from the cathode 8-1 isaccelerated by the anode 9-1 and shaped to be rectangular in a sectionalview in a forming opening arranged at a specified location in theprimary optical system 10-1. The appropriately shaped electron beam isthen contracted to be narrower when the electrostatic (orelectromagnetic) lens 25-1 of a quadrupole or octopole of rotationallyasymmetric type is used to adjust the lens condition. That is, theelectron beam is adjusted by making a contraction factor for therectangular shape in a major axis direction especially large while thecontracting factor in a minor axis direction remained in a limitedrange, so that it is calculated that the beam may be shaped into asquare of 100 nanometers at a location slightly above the deflectionprincipal plane of the E x B separator 30-1. However, because there isan aberration of the lens in the apparatus used in practice, the beamactually measured is a circular beam having a diameter of 120 nanometersat the location slightly above the deflection principal plane of the E xB separator 30-1. The circular electron beam having entered the E x Bseparator 30-1 is deflected thereby into the direction perpendicular tothe surface of the sample S, and then contracted to be a quarter in sizeby the electrostatic objective lens 28-1 thus focused to be an electronbeam having a diameter of about 30 nanometers on the surface of thesample. When the scanning deflector 19-1 is operated so as for thiselectron beam having the diameter of 30 nanometers to scan the surfaceof the sample S in two-dimensional way, accordingly a region of a squareof 5 microns or 100 microns can be scanned.

[0197] The secondary emission beam emitted from the sample S isaccelerated by the accelerating electric field for the secondaryemission beam, which has been applied to the electrostatic objectivelens 28-1, and then passes through said electrostatic lens 28-1 to enterthe E x B separator 30-1. The secondary emission beam having entered theE x B separator 30-1 passes through the electrostatic intermediate lens31-1 and the electrostatic magnifying lens 33-1 of the secondary opticalsystem 20-1 under the same lens condition as in the case of the functionfor the image projection, and then enters the MCP 14-1.

[0198] The secondary emission beam having entered the MCP 14-1,similarly to the case of the function for the image projection,irradiates the fluorescent screen 15-1 so as to form a pattern imagethereon, and then after having passed through the FOP 17-1, the beam isdetected by the CCD camera 18-1 and converted into an electric signal.The electric signals from the CCD camera 18-1 are electrically summedover all of the channels so as to obtain a signal intensity.Accordingly, the location data can be obtained from the scanning time.

[0199] The switching of the function between the function for the imageprojection and the function as the scanning electron microscope can beaccomplished simply through the electrical operations comprising thesteps of: changing a magnification factor of each of the lensesconstructing the quadrupole lens 25-1; giving a scanning signal to thescanning deflector 19-1; and determining whether the output signal fromthe CCD camera 18-1 should be processed by a regular signal processingas the function for the image projection or by a processing for addingthe signals electrically for all of the channels as the scanningelectron microscope.

[0200] According to the second embodiment, the following effects may bebrought about.

[0201] (1) Since the switching between the function for the imageprojection and the function as the scanning electron microscope can beaccomplished by changing electrically the condition of the quadrupolelens and quadrupole deflector, the operation signal to the scanningdeflector, and the signal processing for the signal from the CCD camera,therefore even if there are different kinds of chips formed on a singlewafer with easily-charged chips and hardly-charged chips being includedon the same wafer, a pattern inspection may be performed efficiently byfast switching between said two functions.

[0202] (2) For the mark detection in the registration, highly accuratemark detection can be achieved by using a scanning area reduced to asquare of a few microns with a pixel size as small as 5 nanometers.

[0203] (3) For the pattern inspection, the pattern inspection withhigher throughput can be accomplished by using a pixel size of 50nanometers, which is determined in conjunction with the pixel of the CCDcamera and the magnification factor used in the function for the imageprojection.

(Third Embodiment)

[0204] Since a defect inspection apparatus according to a thirdembodiment employs a defect inspection system using the electron beamapparatus 1-1 of FIG. 1, the similar numeric references are used todesignate the similar components and a detailed description on theconfiguration of this defect inspection apparatus will be omitted.

[0205] For the MCP 14-1 of FIG. 1, it is obvious from FIG. 5, in whichthe operating time is represented along the lateral axis and themultiplication factor is represented along the longitudinal axis, thatthe multiplication factor decreases as the operating time increases.Further, it is also obvious from FIG. 6, which indicate the correlationbetween the voltage applied to the MCP (sometimes referred to as MCPapplied voltage) and the MCP multiplication factor while representingthe MCP applied voltage along the lateral axis and the MCPmultiplication factor along the longitudinal axis, that the MCPmultiplication factor increases in monotone up to a saturation value.Based on this study, the present invention employs an MCP appliedvoltage control circuit 40-3 for performing a control as shown in FIG.7. This MCP applied voltage control circuit 40-3 calculates a currentMCP multiplication factor from an MCP operating time and controls thevoltage to be applied to the MCP such that the MCP multiplication factoris regularly kept at a constant level, based on an MCP appliedvoltage-MCP multiplication factor curve with respect to the currentoperating time. That is, the circuit controls the voltage to be appliedto the MCP such that the voltage is shifted in the direction indicatedby an arrow of FIG. 6. As for an image containing a defect, which hasbeen taken through such a control, a constant level of contrast in theimage can be regularly obtained in spite of the long time use of theMCP. Further, this MCP applied voltage control circuit 40-3 controls thevoltage to be applied to the MCP in such a manner that if the line rateof the line sensor is changed to be doubled as compared to a currentline rate, then the circuit controls the voltage to be applied to theMCP to such a level that can achieve a doubled MCP multiplication factoras compared to the current multiplication factor, and if themagnification factor is changed to be doubled as compared to the currentmagnification factor, then the circuit controls the voltage to beapplied to the MCP to such a level that can achieve an MCPmultiplication factor four times as high as the current multiplicationfactor, and thereby keeps the constant level of contrast of the imageeven in the case of any change in those parameters. It is to be notedthat a flow chart of the MCP applied voltage control circuit 40-3 isshown in FIG. 7.

[0206] A specific embodiment will now be described in more detail inconjunction with a wafer defect inspection.

[0207] A wafer W prepared as a sample subject to a defect inspection asshown in FIG. 8 was loaded on the X-Y stage 26-1, and the primaryelectron beam was radiated upon the wafer W by the aforementioned defectinspection apparatus 1-1 so as to scan the wafer W in the up and downdirections as indicated by an arrows A in FIG. 8 thus to pick up imagescovering whole area on the wafer, and the images taken by the linesensor 18-1 were stored in the PC memory 34-1. These steps of the defectinspection were performed by the MCP applied voltage control circuit40-3 continuously for 1000 hours. As a result, the MCP multiplicationfactor was about 4500 for the operating time of zero hour, and after theoperating time of 1000 hours, G2 was changed to about 3000 for the sameMCP applied voltage of 1200 V (see FIG. 5). However, when the MCPapplied voltage control circuit of the present invention was used tochange the MCP multiplication factor, the MVP applied voltage wasshifted from about 1200 V to about 1400 V while the MCP multiplicationfactor of the constant level of 4500 having been steadily indicatedthrough the period. Further, the defective image taken in such a mannerhad kept the almost same level of contrast in the image over 1000 hours.

[0208] According to the third embodiment, the following effects may bebrought about.

[0209] (A) Any change or deterioration of the contrast in the defectiveimage may be inhibited even after a long time operation of the defectinspection.

[0210] (B) By controlling the MCP applied voltage or the emissioncurrent of the beam, the deterioration of the multiplication factor dueto the long time operation of the MCP can be prevented, and thereby thedefective image contrast can be maintained in the same level through theoperation.

[0211] (C) By determining the MCP applied voltage by referring to thecurrent MCP applied voltage-MCP gain curve, the defective image contrastcan be maintained in the same level through the operation

[0212] (D) The performance in the defect inspection can be improvedwithout any deterioration in throughput.

(Fourth Embodiment)

[0213]FIG. 9 is a schematic plan view of a feed-through unit accordingto an embodiment of the present invention and FIG. 10 is a schematiccross sectional view of the filed-through unit of FIG. 9 taken along theline A-A. The feed-through unit 10-4 of FIG. 9 is composed of asemiconductor device forming a semiconductor package. As shown in FIG.10, the feed-through unit 10-4 comprises a feed-through section 2-4, atleast one electricity introduction pin 5-4 to be fixedly attached tosaid filed-through section 2-4, a wiring 9-4 for interconnecting said atleast one electricity introduction pin 5-4 with a functional element,though not shown, and a metal flange 1-4.

[0214] The feed-through section 2-4 is made of material having anelectric insulating ability, and typically made of alumina-basedceramic. The feed-through section 2-4 is coupled with the metal flange1-4 via a shell 3-4. The shell 3-4 is made of metal such as Kovar or 42alloy, and plays a role of preventing a damage which might be caused bya thermal stress due to a difference in coefficient of thermal expansionbetween the feed-through section 2-4 and the metal flange 1-4. Uponbonding the filed-through section 2-4 with the shell 3-4, for example,molybdenum-manganese metallized and silver solder are used to provide asealing adhesion between them. Further, the coupling between the shell3-4 and the metal flange 1-4 is provided with an air-tight treatment ina method such as the TIG full-arc welding.

[0215] The feed-through section 2-4 comprises a pattern metallizedsection 4-4 and a die (functional element) 6-4. The pattern metallizedsection 4-4 and the pin 5-4 are sealingly adhered to each other via thesilver solder. The die 6-4 is fixedly attached to a die bonding section7-4 formed in one of the surfaces of the feed-through section 2-4. Thedie 6-4 is constituted of a functional element including a sensor, anelectric circuit and a semiconductor element. The field-though section2-4 is adapted to allow an existence of different pressure conditionsand different kinds of gas via the feed-through section 2-4.

[0216] In FIG. 10, the die 6-4 is arranged on a surface on a vacuumatmosphere side of the feed-through section 2-4, and the die 6-4 isconnected to an electricity introduction terminal of the vacuuminsulated pin 5-4. Further, the pin 5-4 is arranged in such a mannerthat the electric signal of the die 6-4 can be extracted out into theatmosphere via the electricity introduction terminal. The feed-throughunit 10-4 shown in FIGS. 9 and 10 is composed of a semiconductor packagehaving a function capable of vacuum-insulating, in specific, a packageaccommodating a semiconductor device such as CCD or TDI. Thisfeed-through unit 10-4 is used as a detector for detecting a defect inthe semiconductor device including an image projecting system, as willbe described later with reference to FIG. 13.

[0217] In the unit shown in FIGS. 9 and 10, the functional element isfabricated on a top surface in the vacuum side of the feed-throughsection 2-4, though not shown. The interconnecting wiring 9-4 forconnecting the electricity introduction pin 5-4 and the functionalelement which is not shown is formed in a net-like geometry on a topsurface of the feed-through section 2-4. The feed-through section 2-4 iswelded to the metal flange 1-4 or coupled with the metal flange 1-4 viathe shell 3-4.

[0218] The feed-through section 2-4 may or may not include partially adrop-in section formed thereon as a die bonding section 7-4. As for amethod to be used for the adhesion in the die bonding section 7-4, anadhesive, an adhesive tape and a soldering by a metal of low fusingpoint may be applicable. If it is to be used in the vacuum atmosphere,preferably a method which resultantly provides small quantity ofoutgassing in the vacuum should be used. In the embodiment of FIG. 10,although the interconnecting wiring 9-4 has been employed as theelectric connection means between the die pad section 8-4 and thepattern metallized section 4-4, a flip chip connection or an ordinaryelectric wiring may be employed instead.

[0219]FIG. 11 is a schematic plan view of a feed-through unit accordingto another embodiment of the present invention, showing one quarter of aplane of a functional element 6-4. FIG. 12 is a schematic crosssectional view of the feed-through unit 6-4 of FIG. 11 taken along theline B-B. FIGS. 11 and 12 shows a feed-through unit 20-4 having a largernumber of pins 5-4. The same method as that used in the embodiment 10 isemployed to secure sealingly the feed-through section 2-4 to the metalflange which is not shown.

[0220] If the feed-through unit 20-4 has an excessively large number ofpins 5 as shown in FIGS. 11 and 12 and accordingly the lower patternmetallized 12-4 is not sufficient to form all of the wirings, then awiring plate 15-4 equipped with an upper pattern metallized 16-4fabricated on a top surface thereof may be built so as to besuperimposed thereon, wherein the lower and the upper patternsmetallized 12-4, 16-4 are electrically connected to the die 6-4 by usinga lower and an upper connecting wirings 19-4, 18-4 respectively. Theelectric connection between the upper pattern metallized 16-4 and thepin 5-4 may be provided by using either one of a brazing, a soldering,or a wire bonding.

[0221]FIG. 13 is a schematic longitudinal cross sectional view of awafer defect inspection apparatus 30-4 incorporated with thefeed-through unit 10-4 or 20-4 according to the present invention. Thewafer defect inspection apparatus 30-4 of FIG. 13 comprises an electrongun 22-4 for emitting an electron beam 41-4 into a vacuum chamber 21-4,an illumination optical system 23-4 consisting of a group ofelectrostatic lenses, a stage 24-4 for supporting a wafer to beinspected, an image projecting optical system 26-4 consisting of a groupof electrostatic lenses, and a detector 40-4.

[0222] As shown in FIG. 13, the detector 40-4 comprises an MCP (MicroChannel Plate) 31-4 for amplifying a secondary electron image, afluorescent screen 32-4 for converting the electron image amplified bythe MCP 31-4 into an optical signal, a FOP (Fiber Optic Plate,designated with a reference numeral 28-4) disposed so as to be tightlyattached to the fluorescent screen 32-4 for transmitting the opticalimage converted by the fluorescent screen 32-4, an element 20-4(functional element 6-4) for converting the optical image output fromthe FOP 28-4 into a digital electric signal, the feed-through unit 10-4,and a camera 29-4 disposed just above the feed-through unit forconverting the electric signal from the feed-through unit. Thefiled-through unit 10-4 transmits the electric signal to an outsidewhile providing a sealing for the vacuum system within the vacuumchamber 21-4 against the outside. The MCP 31-4, the fluorescent screen32-4 and the FOP 28-4 are all supported by a common support member so asto form an MCP/FOP assembly 27-4.

[0223] In the wafer defect inspection apparatus 30-4 of FIG. 13, theelectron beam 41-4 emitted from the electron gun 22-4 is deflected andshaped appropriately by the illumination optical system 23-4 and thenradiated upon a surface of the wafer 25-4 loaded on the stage 24-4. Thesecondary electrons emitted from the wafer 25-4 by the irradiation ofthe electron beam are formed into an image on the MCP/FOP assembly 27-4by the image projecting optical system 26-4 at a predeterminedmagnification. The secondary electron image formed on the MCP/FOPassembly 27-4 is multiplied and converted into an optical signal by thefluorescent screen 32-4, and the signal enters to the feed-through unit10-4, where the optical signal is converted into a digital signal by thefunctional element on the feed-through unit, and then this digitalsignal is transmitted to the camera 29-4. The camera 29-4 converts thedigital signal into to a signal in such a form that an image processingunit (not shown) in the subsequent step can accept, and then outputs thesignal thus to be used in the wafer defect inspection and the like.

[0224] According to the fourth embodiment of the present invention,since such a configuration has been employed that comprises at least oneelectricity introduction pin fixedly attached to the feed-throughsection and the interconnecting wiring for connecting said at least oneelectricity introduction pin and the functional element, wherein becausesaid functional element includes a sensor, a signal delay may beprevented and a disturbance may be reduced with a shorter signal line incomparison with a configuration where an image taking sensor and avacuum flange are formed separately, and thus the sensor may be drivenat a high speed, therefor the throughput of the defect inspection can beimproved

[0225] The wafer defect inspection apparatus using the electron beamapparatus incorporated with the feed-through unit according to thefourth embodiment of the present invention can inspect a semiconductordevice having a fine pattern with a high level of throughput and canprevent any faulty products from being delivered.

(Fifth Embodiment)

[0226]FIG. 14 schematically shows a configuration of a defect inspectionapparatus according to an embodiment of the present invention. Theinspection apparatus of FIG. 14 is a defect inspection apparatus of theimage projection type similar to that in the embodiment of FIG. 13, inwhich a primary electron beam 5-5 emitted from an electron gun 15 passesthrough a primary electron optical system and irradiates a sample 10-5,and a secondary electron beam emitted from the sample 10-5 by saidirradiation is introduced into a detector 14-5 via a secondary electronoptical system, where an image data representing a pattern of a surfaceof the sample 10-5 may be obtained so as to perform a defect inspection.

[0227] The electron gun 1-5 comprises a cathode made of LaB₆, saidcathode having a flat <100> monocrystal surface with a diameter greaterthan 100 microns formed in a tip portion thereof. In the primaryelectron optical system, the primary electron beam 5-5 emitted from theelectron gun 1-5 is, after the emission current amount having beencontrolled by the Wehnelt electrode 2-5, accelerated by a plurality ofpositive electrodes 3-5 and forms a crossover in a gun aperture 4-5.Then, the primary electron beam 5-5 enters to an electrostatic lens 6-5,in which the beam is shaped to be rectangular or elliptical in asectional view and goes straight through an alignment electrode 7-5 andinto a Wien filter 8-5. The Wien filter 8-5 deflects the primaryelectron beam 5-5 so that the beam is radiated onto the sample 10-5 at aright angle and thus, the beam irradiates the sample 10-5 loaded on anX-Y stage 9-5. At that time, the primary electron beam 5-5 may be, forexample, elliptical in the section having the size of 400 microns×600microns. The primary electron beam 5-5 is controlled by a retardingvoltage applied to the sample 10-5 so as to have a predetermined landingenergy and then is radiated onto the sample 10-5, and in response tothis irradiation the sample emitts the secondary electrons.

[0228] The secondary electron beam thus emitted from the sample 10-5 isadvanced straight forward through the Wien filter 8-5 and after havingbeen magnified by an electrostatic lens 11-5 in the secondary electronoptical system with a predetermined lens magnification, the beam isformed into an image on a micro channel plate 12-5. The secondaryelectron beam having been formed into the image on the micro channelplate 12-5 is multiplied by the micro channel plate 12-5 and projectedonto a fluorescent screen 13-5. The secondary electron beam is convertedby the fluorescent screen 13-5 into light, which is then entered into adetector 14-5 such as a CCD camera, a line sensor or the like. In thisway, a pattern image for the surface of the sample 10-5 is obtained andthe obtained image is fed to an image processing section 15-5.

[0229] Further, the defect inspection apparatus of FIG. 14 comprises acontrol section 16-5 for controlling a voltage applied to the Wehneltelectrode 2-5 and the positive electrode 3-5, and a power supply 18-5for supplying the Wehnelt electrode 2-5 and the positive electrode 3-5with the voltage at a certain level based on a command from the controlsection 16-5. The reason why the control section 16-5 has been providedis that only by changing the voltage to be applied to the Wehneltelectrode 2-5 in association with the elapsed time measured from thebeginning of the current emission of the electron gun 1-5, the emissioncurrent of the electron gun 1-5 can be maintained at a certain value.However, if the applied voltage to the Wehnelt electrode 2-5 is changed,a cross over diameter of the primary electron beam is also changed. Toprevent this, the control section 16-5 also changes a voltage applied tothe positive electrode 3-5 while changing the voltage applied to theWehnelt electrode 2-5, so that the primary electron beam may always forma crossover at the center of the gun aperture 4-5. Such a controllingallows the image processing section 15-5 to obtain an image having acertain level of contrast.

[0230] To accomplish this, in the defect inspection apparatus of FIG.14, a relationship between the elapsed time measured from the beginningof the current emission and the applied voltage to the Wehnelt electrode2-5 required to control the emission current of the electron gun 1-5 tobe maintained at a constant level and also a relationship between thechange in the applied voltage to the Wehnelt electrode 2-5 and thevoltage applied to the positive electrode 3-5 required for the primaryelectron beam to form the crossover at the center of the gun aperture4-5 should be measured in advance, and for said emission current, therelationship between the elapsed time and the applied voltage should bestored in the control section 16-5 in a form of a look-up table 17-5.

[0231] When the defect inspection apparatus of FIG. 14 is operated afterthe above-described pre-processing having been finished, the controlsection 16-5 monitors the elapsed time from the beginning of the currentemission and refers to the look-up table 17-5 with a predetermined timeinterval while reading a value representing a voltage to be appliedcorresponding to said elapsed time from the beginning of the currentemission and applying said value to the power supply 18-5 so as tocontrol the emission current of the electron gun 1-5 to be kept at aconstant level, and thereby the control section 16-5 can set the voltageto be applied to the Wehnelt electrode 2-5 to a certain levelcorresponding to said elapsed time. At the same time, the controlsection 16-5 also reads out a value representing the voltage to beapplied to the positive electrode 5-3 corresponding to a change in thevoltage applied to the Wehnelt electrode 2-5 from the look-up table 17-5and applies the read value to the power supply 18-5, thereby adjustingthe voltage to be applied to the positive electrode 3-5 to a desiredvalue.

[0232] According to an actual experiment in which a level of voltage tobe applied to the Wehnelt electrode 2-5 in order to maintain theemission current at a constant level of 30 microampere was measured as afunction of the elapsed time from the beginning of the current emissionby using the defect inspection apparatus having the configuration shownin FIG. 14, it has been observed that the voltage to be applied to theWehnelt electrode 2-5 was around the level of −300 volts at thebeginning of the current emission, around the level of −350 volts after10 hours, around the level of −400 volts after 100 hours, and around thelevel of −450 volts after 1000 hours, as shown in FIG. 15. Further, theapparatus could successful control such that the primary electron beammight formed the crossover at the center of the gun aperture 4-5.

[0233] In contrast to the result shown in FIG. 15, it is obvious fromFIG. 16 of a graph indicating a relationship between the voltage appliedto the Wehnelt electrode (by volt) and the emission current of theelectron gun (by microampere) according to the prior art, that theemission current increases rapidly as the voltage applied to the Wehneltelectrode exceeds the level of −300 volts.

[0234] As having been understood from the description of the electronbeam apparatus according to the fifth embodiment, since the apparatus ofthe present embodiment allows the voltage applied to the Wehneltelectrode to be changed in association with the passage of time so as tokeep a certain level of emission current from the electron gun,therefore an image for a sample with a certain level of contrast can beobtained, and most effectively a sample can be inspected for a defectwith high degree of throughput and accuracy.

(Sixth Embodiment)

[0235] A further detailed system for an entire defect inspection systemincluding the conveying mechanism 40-1, the vibration isolatingmechanism and the vacuum system as described with reference to FIG. 1will now be described as a sixth embodiment of the present invention.

[0236]FIGS. 17 and 18 show main components of a semiconductor inspectionapparatus 1 according to the sixth embodiment, in an elevation view anda plan view respectively.

[0237] The semiconductor inspection apparatus 1 of the presentembodiment comprises a cassette holder 10 for holding a cassetteaccommodating a plurality of wafers, a mini-environment device 20, amain housing 30 defining a working chamber, a loader housing 40 disposedbetween the mini-environment device 20 and the main housing 30 so as todefine two loading chambers, a loader 60 for loading a wafer from thecassette holder 10 onto a stage unit 50 located within the main housing30, and an electron optical unit 70 installed within a vacuum housing,all of which are arranged with the physical relationship as shown inFIGS. 17 and 18. The semiconductor inspection apparatus 1 furthercomprises a pre-charge unit 81 disposed within the vacuum main housing30, a potential applying mechanism 83 (shown in FIG. 25) for applying apotential to the wafer, an electron beam calibration mechanism 85 (shownin FIG. 27), and an optical microscope 871 which is a component of analignment control unit 87 used for positioning the wafer on the stageunit.

[0238] The cassette holder 10 has been designed so that it can hold aplurality (two in this embodiment) of cassettes “c” (e.g., a closedcassette such as SMIF or FOUP available from Assist Corp.) accommodatinga plurality of wafers (e.g., 25 pieces of wafers) which are arranged inparallel in the up and down direction within the cassette. As for thiscassette holder, any cassette holder may be arbitrarily selected andinstalled in the apparatus depending on the circumstance, wherein forexample, if the cassette is conveyed by a robot or the like and isautomatically loaded to the cassette holder 10, the cassette holder in astructure suitable for such specific operation may be selected, and ifthe cassette is loaded manually, a cassette holder in an open cassettestructure may be selected. In this embodiment, such type of cassetteholder 10 is employed that is suitable for the circumstance where thecassette c is automatically loaded, wherein said cassette holder 10comprises, for example, an elevating table 11 and an elevating mechanism12 for moving up and down the elevating table 11, in which the cassettec is allowed to be set on the elevating table automatically in a stateindicated by a chained line of FIG. 18 and after having been setthereon, to be rotated automatically into a state indicated by a solidline of FIG. 18 so that the cassette is oriented to a rotary movementaxis line of a first conveying unit in the mini-environment device.Further, the elevating table 11 is lowered into a state indicated by achained line of FIG. 17. In this way, since any cassette holders in anyknown structures may be used appropriately depending on thecircumstance, including the cassette holder used in the automaticloading or the cassette holder used in the manual loading, the detaileddescription on those structures and functions will be herein omitted.

[0239] In another embodiment shown in FIG. 28, a plurality of 300 mmsubstrates W is accommodated in a state of being contained in a slottype pocket (not shown) fixedly attached to an inner side of a box mainbody 501 so as to be ready for the conveying and storing. This substratestorage box 24 comprises: a box main body 501 of rectangular-cylindricalshape; a door 502 for carrying in/out the substrate, which is coupledwith an automatic door opening/closing unit for selectively opening orclosing said door 502 so that an opening in a side face of the box mainbody 501 can be opened or closed by this mechanism; a lid body 503disposed in an opposite side of said opening for covering anotheropening through which filters and a fun motor are to be attached ordetached; said slot type pocket for holding the substrate W; a ULPAfilter 505; a chemical filter 506; and a fan motor 507. In thisembodiment, the substrate is carried in or out by a first conveying unit61 of robot type in the loader 60.

[0240] It is to be noted that the substrate or the wafer received in thecassette c is a wafer to be subjected to an inspection, and suchinspection may be carried out after or in a course of a process forprocessing the wafer in the semiconductor manufacturing process. Inspecific, such a substrate or a wafer as having been subjected to amembrane deposition process, a CMP process or an ion implantationprocess, a wafer with a wiring pattern formed thereon, or a wafer with awiring pattern not yet formed thereon is received in the cassette. Sincea plurality of wafers are received in the cassette c so as to bearranged horizontally and parallelly placing a space therebetween andstacked vertically, an arm of the first conveying unit is designed to bemovable vertically so that the first conveying unit can catch the waferin any arbitrary location.

[0241] In FIGS. 17 to 19, the mini-environment device 20 comprises ahousing 22 defining a mini-environmental space 21 subject to anatmosphere control, a gas circulation unit 23 for circulating a gas suchas a clean air within the mini-environmental space 21 for the atmospherecontrol, a pumping unit 24 for recovering and exhausting a part of theair supplied to the mini-environmental space 21, and a pre-aligner 25disposed in the mini-environmental space 21 for roughly positioning thesubstrate or the wafer as an objective material to be inspected.

[0242] The housing 22 has a top wall 221, a bottom wall 222 and fourside walls for forming a closed space, thus having a structure to shieldthe mini-environmental space 21 from the outside. In order to controlthe atmosphere within the mini-environmental space 21, the gascirculation unit 23, as shown in FIG. 19, comprises a gas supply unit231 attached to the top wall 221 within the mini-environmental space 21for cleaning a gas (an air in this embodiment) and blowing the clean airjust downward in laminar flow through one or more gas outlets (notshown), a recovery duct 232 disposed on the bottom wall 222 within themini-environmental space for recovering the air which has flowed downtoward the bottom, and a conduit 233 interconnecting the recovery duct232 and the gas supply unit 231 for returning the recovered air back tothe gas supply unit 231. Although in this embodiment the gas supply unit231 has been designed so that about 20% of the supply air may be takenfrom the outside of the housing 22 so as to clean the air, the ratio ofthe air to be taken from the outside may be selected arbitrarily. Thegas supply unit 231 is equipped with either of the HEPA filter or theULPA filter with a known structure for generating a clean air. A downflow of the clean air in laminar flow, namely, a down flow of the air ismainly supplied so as to flow through a conveying plane by means of thefirst conveying unit disposed in the mini-environment device 21, therebypreventing dust from depositing on the wafer, which otherwise may beprobably caused by the conveying unit. Accordingly, the injection portof the down flow is not necessarily arranged in the location near thetop wall as illustrated, but it may be arranged at any location abovethe conveying plane by means of the conveying unit. Also, the down flowis not necessarily supplied to flow over the entire area of themini-environmental space. It is to be noted, in some cases, an ionicwind may be used as the clean air to ensure the level of cleanness.Further, a sensor may be arranged in the mini-environmental space sothat the unit can be shut down in case of deterioration in the level ofcleanness. An entrance and exit port 225 is formed in a portion adjacentto the cassette holder 10 among the side walls 223 of the housing 22. Ashutter unit of known structure may be provided in the vicinity of theentrance and exit port 225 so that the entrance and exit port can beclosed from the side of the mini-environment device. The down flow inthe laminar flow generated in the vicinity of the wafer may have a flowvelocity of, for example, 0.3 to 0.4 m/sec. The gas supply unit is notnecessarily arranged within the mini-environmental space but may bearranged in the outside of the space.

[0243] The pumping unit 24 comprises a suction duct 241 disposed in anunder portion of said conveying unit at a location lower than the waferconveying plane of the conveying unit, a blower 242 disposed in theoutside of the housing 22, and a conduit 243 interconnecting the suctionduct 241 and the blower 242. This pumping unit 24 sucks from the suctionduct 241 the gas flowing down around the conveying unit and includingthe dust, which may be possibly generated by the conveying unit, andexhaust the gas to the outside via the conduit 243, 244 and the blower242. In that case, the gas may be exhausted into an exhaust pipe (notshown) lying in the vicinity of the housing 22.

[0244] The aligner 25 arranged within the mini-environmental space 21 isdesigned such that it may detect optically or mechanically anorientation-flat formed in the wafer (which is a flat portion formed inan outer periphery of a circular wafer, and hereafter referred to asori-fla) and/or a one ore more V-shaped cut-outs, namely, notches formedin an outer-peripheral edge of the wafer, and then position the wafer inadvance in the rotational direction around the axis line O-O with aprecision of +/−1 degree. The pre-aligner is a component of a mechanismfor determining a coordinate of the objective sample to the inspectionaccording to the present invention as defined in the attached claim, andplays a role for roughly positioning the objective material to beinspected. This pre-aligner itself may be of known structure and anexplanation on the structure and operation thereof will be hereinomitted.

[0245] It is to be noted that a recovery duct may be additionallyprovided in a lower portion of the pre-aligner, though not shown, sothat an air including the dust, which has been discharged from thepre-aligner, can be exhausted to the outside.

[0246] In FIGS. 17 and 18, the main housing 30 defining a workingchamber 31 comprises a housing main body 32, and the housing main body32 is supported by a housing support unit 33 mounted on a vibrationisolating unit, namely, a vibration isolating unit 37 disposed on atable frame 36. The housing support unit 33 comprises a frame structure331 configured in a rectangular shape. The housing main body 33 isfixedly installed on the frame structure 331 and comprises a bottom wall321 mounted on the frame structure 331, a top wall 322 and four sidewalls 323 connected to the bottom wall 321 and the top wall 322, therebydefining a closed space so as to isolate the working chamber 31 from theoutside. Although the bottom wall 321, in this embodiment, is made ofrelatively thick steel plate so as to prevent a distortion which maypossibly be generated by a load applied from a device such as the stageto be mounted thereon, other structure may be used. In this embodiment,the housing main body and the housing support unit 33 has beenconstructed in a rigid structure, and the vibration isolating unit 37 isprovided to prevent the vibration from being transmitted to this rigidstructure from a floor on which the table frame is installed. Anentrance and exit port 325 for carrying in/out a wafer is formed in oneof the side walls 323 of the housing main body 32 adjacent to the loaderhousing, which will be described later.

[0247] It is to be noted that the vibration isolating unit may be ofactive type or passive type, either of which may have an air spring, amagnetic bearing or the like. The vibration isolating unit may be of anyknown structure and an explanation on its structure and functions willbe omitted. The working chamber 31 is designed to be held in vacuumatmosphere by a vacuum unit (not shown) of known structure. A controlunit 2 is arranged under the table frame 36 so as to control a generaloperation of the unit.

[0248] In FIGS. 17, 18 and 20, the loader housing 40 comprises a housingmain body 43 defining a first loading chamber 41 and a second loadingchamber 42. The housing main body 43 has a bottom wall 431, the top wall432, four side walls 433 defining a closed space, and a partition wall434 for partitioning the housing into the first loading chamber 41 andthe second loading chamber 42 so as to isolate the both loading chambersfrom the outside. An opening, namely, an entrance and exit port 435 isformed in the partition wall 434 for giving and taking the wafer betweenthe both loading chambers. In addition, entrance and exit ports 436 and437 are formed in the side walls 433 in those portions adjacent to themini-environment device 20 or the main housing 30 respectively. Thehousing main body 43 of this loader housing 40 is mounted on andsupported by the frame structure 331 of the housing support unit 33.Accordingly, also this loader housing 40 is designed so as to beisolated from the vibration of the floor. The entrance and exit port 436of the loader housing 40 and the entrance and exit port 226 of thehousing 22 of the mini-environment device are in alignment with eachother, and a shutter unit 27 is arranged therebetween so as to blockselectively a communication between the mini-environmental space 21 andthe first loading chamber 41. The shutter unit 27 has a sealing member271 surrounding the peripheries of the entrance and exit ports 226 and436 and secured by way of a tight contact to the side wall, a door 272for working cooperatively with the sealing member 271 to block an airflow through the entrance and exit ports, and a driving unit 273 fordriving the door. Further, the entrance and exit port 437 of the loaderhousing 40 and the entrance and exit port 325 of the housing main body32 are in alignment with each other, and a shutter unit 45 is arrangedtherebetween so as to block selectively a communication between thesecond loading chamber 42 and the working chamber 31. The shutter unit45 has a sealing member 451 surrounding the peripheries of the entranceand exit ports 437 and 325 and secured by way of a tight contact to theside walls 433 and 323, a door 452 for working cooperatively with thesealing member 451 to block an air flow through the entrance and exitports, and a driving unit 453 for driving the door. Still further, theopening formed in the partition wall 433 is provided with a shutter unit46 so that the opening may be closed by a door 461 and a communicationmay be selectively blocked by way of sealing between the first and thesecond loading chambers. Those shutter units 27, 45 and 46 are adaptedto seal air-tightly the respective chambers when they are in the closingmode. Since those shutter units may be of known structures, explanationson their structures and operations will be omitted. It is to beappreciated that the supporting manner of the housing 22 of themini-environment device 20 is different from the supporting manner ofthe loader housing 40, and accordingly a damping material for isolatingthe vibration may be arranged between the housing 22 and the loaderhousing 40 surrounding the peripheries of the entrance and exit ports inthe air-tight manner in order to prevent the vibration from the floorfrom being transmitted to the loader housing 40 and thus the mainhousing 30 via the mini-environment device 20.

[0249] A wafer rack 47 is installed within the first loading chamber 41,which wafer rack holds a plurality of wafers (two wafers in thisembodiment) in a horizontal state while isolating one from another inthe up and down direction. The wafer rack 47 comprises support rods 472secured to a rectangular base plate 471 at four corners respectively inupright state separately from one another, and a two-step of supportsections 473 and 474 is formed in each of the support rods 472 so as tosupport the wafers W in the peripheral edges thereof loaded on thesupport sections respectively. Then, tip portions of arms of the firstand the second conveying units, which will be described later, areadvanced through a space between the adjacent support rods and approachthe wafers so as to grip the wafers with the arms.

[0250] The loading chambers 41 and 42 are specifically designed suchthat the atmosphere in the chambers can be controlled to high level ofvacuum condition (a vacuum level of 10⁻⁵ to 10⁻⁶ Pa) by a vacuum pumpingunit (not shown) of known structure including a vacuum pump, though notshown. In that case, the first loading chamber 41 may be controlled tobe a low level of vacuum atmosphere as a low level vacuum chamber andthe second loading chamber 42 may be controlled to be a high level ofvacuum atmosphere as a high level vacuum chamber, so as to preventeffectively a contamination of the wafer. Employing such a structureallows the wafer, which has been contained within the loading chamberand is going to be inspected subsequently for a defect, to be fed intothe working chamber without any delay. Employing such a loading chambertogether with the principle of an electron beam apparatus of themulti-beam type, which will be described later, helps improve thethroughput of the defect inspection and also allows the vacuum level inthe surrounding of the electron source to be kept as high as possible,said electron source being required to be held in a storage conditionhaving a high level of vacuum atmosphere.

[0251] The first and the second loading chambers 41 and 42 are connectedwith a vacuum pumping pipe and a vent pipe for an inert gas (e.g., drypure nitrogen) respectively (both not shown). In this way, theconditions of an atmospheric pressure in the respective loading chambersmay be accomplished by the inert gas vent (injecting the inert gas andthereby preventing other gas than the inert gas such as oxygen gas frombeing adsorbed on the surface). Since the unit itself for performingsuch an inert gas vent may have a known structure, the detailedexplanation thereof will be omitted.

[0252] It is to be noted that in an inspection apparatus using anelectron beam according to the present invention, if a substance such aslanthanum hexaboride (LaB₆), which is typically used as an electronsource in an electron optical system as will be described later, is onceheated to such high temperature as it emits thermal electron, it becomesimportant that the LaB₆ should be isolated from any contact with oxygenor the likes in order not to shorten its life-time, and this will bemuch ensured by applying the atmosphere control as described above in astage prior to carrying the wafer into the working chamber in which theelectron optical system is located.

[0253] The stage unit 50 comprises a stationary table 51 located on thebottom wall 321 of the main housing 30, a Y table 52 which moves in theY-direction (the direction normal to page space in FIG. 17) on thestationary table, an X table 53 which moves in the X-direction (the leftand right direction in FIG. 17) on the Y table, a turn table 54 capableof turning on the X table, and a holder 55 located on the turn table 54.The holder 55 holds a wafer on a wafer loading face 551 thereof whileallowing the wafer to be released. The holder 55 may be of knownstructure so far as it can hold the wafer while allowing the wafer to bereleased mechanically or by way of an electrostatic chuck method. Thestage unit 50 has been designed such that it uses a servo motor, anencoder and a variety of sensors (not shown) to actuate a plurality oftables as described above, and thereby it can position the wafer held bythe holder on the loading face 551 with high level of accuracy in the X,Y and Z directions (Z directions designating the up and down directionin FIG. 17) with respect to the electron beam radiated from the electronoptical system as well as the rotational direction (θ direction) aroundan axis line perpendicular to the support face of the wafer. It is to beappreciated that the positioning in the Z direction may be accomplished,for example, by a design allowing a fine tuning of the position of theloading face on the holder in the Z direction. In that case, a referenceposition of the loading face is detected by a position measuring unit bymeans of a laser having an minute diameter (a laser-interferometertaking advantage of an interferometer) and the position may becontrolled by using a feedback circuit though not shown, andadditionally or alternatively the notch or the ori-fla of the wafer ismeasured so as to detect a planer location and a rotational location ofthe wafer with respect to the electron beam and the turn table may berotated by, for example, a stepping motor controllable by a minuteangle, thereby controlling the position of the wafer. In order toprevent the generation of dust within the working chamber as much aspossible, servo motors 521, 531 and encoders 522, 532 for the stage unitare disposed in the outside of the main housing 30. It is to be notedthat since the stage unit 50 may be of known structure, for example, theone which has been typically used in the stepper, a detailed descriptionon the structure and operation thereof will be omitted. Further,above-described laser-interferometer may be of known structure, adetailed description on the structure and operation thereof will beomitted also.

[0254] A signal obtained by entering in advance the rotational positionand/or the X and the Y positions of the wafer with respect to theelectron beam to a signal detecting system or an image processingsystem, which will be described later, may also be standardized.Further, a wafer chucking mechanism arranged in this holder has beendesigned such that a voltage for chucking the wafer may be applied to anelectrode of an electrostatic chuck so as to press and thus position thewafer at three points on the outer periphery of the wafer (preferably,equally spaced in the circumferential direction). The wafer chuckingmechanism comprises two stationary positioning pins and one cramp pin ofcompressive type. The cramp pin is adapted to accomplish an automaticchucking and an automatic releasing and constitutes a conductive partfor the voltage application.

[0255] It is to be appreciated that although in this embodiment, a tabletraveling in the left and right direction has been designated as the Xtable and a table traveling in the up and down direction as the Y tablein FIG. 18, the table traveling in the left and right direction may bedesignated as the Y table and the table traveling in the up and downdirection as the X table in FIG. 18.

[0256] The loader 60 comprises a first conveying unit 61 of robot typedisposed within the housing 22 of the mini-environment device 20 and asecond conveying unit 63 of robot type disposed within the secondloading chamber 42.

[0257] The first conveying unit 61 has a multi-joint arm 612 capable ofrotating around an axis line O₁-O₁ with respect to a driving section611. Although any multi-joint arm in an arbitrary structure may be used,this embodiment has employed the arm composed of three parts rotatablycoupled to each other. One of those parts forming the arm 612 of thefirst conveying unit 61, which is a first part closest to the drivingsection 611, is attached to a shaft 613 capable of being rotationallydriven by a driving mechanism (not shown) having a known structurearranged within the driving section 611. The arm 612 can be rotatedaround the axis line O₁-O₁ by the shaft 613, and also is madestretchable as a whole unit in a radial direction with respect to theaxis line O₁-O₁ by way of relative rotation of the parts to one another.A tip portion of a third part farthest to the shaft 613 of the arm 612is provided with a gripping unit 616 by means of a mechanical chuck, anelectrostatic chuck or the like having a known structure for grippingthe wafer. The driving section 611 is movable in the up and downdirection by an elevating mechanism 615 of known structure.

[0258] In this first conveying unit 61, the arm 612 stretches toward oneof two cassettes “c” held by the cassettes holder, that is, along adirection of either of M1 or M2, and loads one of the wafersaccommodated in the cassette c onto the arm or grips the wafer with thechuck (not shown) attached in the tip portion of the arm so as to takeout the wafer. After that, the arm is retracted (into a state as shownin FIG. 18) and turns and stops a position where the arm can stretchtoward the direction of M3 of the pre-aligner 25. Then, the armstretches again and loads the wafer having held by the arm, on thepre-aligner 25. On the other hand, after the arm having received thewafer from the pre-aligner 25 in the procedure reversely to theaforementioned, the arm turns again and stops at a position where thearm can stretch toward the second loading chamber 41 (in the directionof M4) and passes the wafer to a wafer receiver 47 within the secondloading chamber 41. It is to be noted that when the wafer ismechanically gripped, the wafer should be gripped in a rim portion (in arange of about 5 mm from the peripheral edge). This is because the waferincludes devices (circuit wirings) formed in the entire region thereofexcluding the rim portion and gripping of the wafer in this deviceregion may cause a break or defect in the device.

[0259] Since the second conveying unit 63 has a structure which isbasically same as that for the first conveying unit 61 but they aredifferent only in the point that the second conveying unit 63 carriesthe wafer between the wafer rack 47 and a loading face of the stageunit, a detailed description will be omitted.

[0260] In this loader 60, the first and the second conveying units 61and 63 convey the wafer from the cassette held by the cassette holderonto the stage unit 50 disposed within the working chamber 31 or viceversa while holding the wafer almost horizontally, and accordingly theoccasions that the arms of the conveying units move upward or downwardare only limited to the time of taking/inserting the wafer out of/intothe cassette, the time of loading/taking the wafer onto/out of the waferrack, and the time of loading/taking the wafer onto/out of the stageunit. Therefore, the conveying of a large wafer having a diameter of,for example, 30 cm may be performed smoothly.

[0261] Now, how to convey the wafer from the cassette c held by thecassette holder to the stage unit 50 disposed within the working chamber31 will be described according to the sequence.

[0262] As discussed above, if the cassette is loaded manually, acassette holder in a structure suitable for the manual operation may beselected and if the cassette is automatically set, a cassette holder ina structure suitable for the automatic operation may be selected. Inthis embodiment, when the cassette c is set on the elevating table 11 ofthe cassette holder 10, the elevating table 11 is lowered by theelevation mechanism 12 so as for the cassette c to be in alignment withthe entrance and exit port 225.

[0263] When the cassette is in alignment with the entrance and exit port225, a cover (not shown) arranged in the cassette is opened, while thecylindrical cover is arranged between the cassette c and the entranceand exit port 225 of the mini-environment device so as to shield theinterior of the cassette and the inner space of the mini-environmentdevice from the outside. Since this structure has been well known in theart, a detailed description on its structure and operation will beomitted. It is to be appreciated that if the shutter unit for openingand closing the entrance and exit port 225 is arranged on the side ofthe mini-environment device 20, the shutter unit is actuated to open theentrance and exit port 225.

[0264] On the other hand, the arm 612 of the first conveying unit 61 hasstopped in the position toward either of the direction M1 or M2 (towardthe direction of M1 in this description), and as the entrance and exitport 225 is opened, the arm stretches and receives in its tip portionone of the wafers accommodated in the cassette. It is to be noted thatthe adjustment of the relative positions of the arm and the wafer to betaken out from the cassette in the up and down direction has beenperformed by the upward and downward movement of the driving section 611and the arm 612 of the first conveying unit 61 in this embodiment, butthe adjustment may be accomplished by the upward and downward movementof the elevating table of the cassette holder or otherwise by thecombination of both.

[0265] As the arm 612 has received the wafer, the arm is retracted andthe shutter unit is actuated to close the entrance and exit port (if theshutter unit has been provided), and then the arm 612 rotates around theaxis line O₁-O₁ and positions itself to be stretchable toward thedirection M3. Next, the arm stretches and loads the wafer having loadedon the tip portion of the arm or having gripped by the chuck onto thepre-aligner 25, and the pre-aligner 25 positions the wafer in anorientation in the rotational direction (the orientation of the waferaround the central axis line perpendicular to the plane of the wafer)within a determined range. After the positioning having been finished,the conveying unit 61 receives the wafer from the pre-aligner 25 intothe tip portion thereof and then retracts the arm so as to be ready forstretching out the arm toward the direction M4. Then, the door 272 ofthe shutter unit 27 moves to open the entrance and exit ports 226 and436, and the arm 612 stretches to load the wafer onto an upper rack or alower rack of the wafer rack 47 in the first loading chamber 41. Asdescribed above, before the shutter unit 27 opens the door and the waferis passed to the wafer rack 47, the opening 435 formed in the partitionwall 434 has been closed in the air tight condition by the door 461 ofthe shutter unit 46.

[0266] In the conveying process of the wafer by the first conveying unitas described above, a clean air flows in a laminar flow (as a down flow)from the gas supply unit 231 arranged in the upper portion of thehousing of the mini-environment device, which prevents dust fromdepositing on the wafer in the course of conveying. A portion of the airin the surrounding of the conveying unit (about 20% of the air suppliedfrom the supply unit and mainly the dirty air in this embodiment) issucked from the suction duct 241 of the pumping unit 24 and evacuated tothe outside of the housing. The rest of the air is recovered via therecovery duct 232 arranged in the bottom portion of the housing andagain returned to the air supply unit 231.

[0267] When the wafer is loaded into the wafer rack 47 within the firstloading chamber 41 of the loader housing 40 by the first conveying unit61, the shutter unit 27 closes the door to seal up the loading chamber41. Then, after the first loading chamber having been full up with theinert gas and the air having been cleaned out, said inert gas is alsoexhausted, and then the loading chamber 41 is brought into the vacuumatmosphere. The level of this vacuum atmosphere in the first loadingchamber may be set to low. As a certain level of the vacuum is obtainedin the loading chamber 41, the shutter unit 46 is actuated to open theentrance and exit port 434 which has been closed with the door 461, andan arm 632 of the second conveying unit 63 stretches and receives onewafer from the wafer receiver 47 with the gripping unit in the tipportion thereof (by loading the wafer on the tip portion thereof orgripping the wafer by the chuck attached to the tip portion thereof). Asthe wafer has been received, the arm is retracted, and the shutter unit46 is actuated again to close the entrance and exit port 435 with thedoor 461. It is to be noted that before the shutter unit 46 opens, thearm 632 has been already brought into a position ready for stretchingtoward the direction N1 for the wafer rack 47. Further, as describedabove, before the shutter unit 46 opens, the entrance and exit ports437, 325 have been closed with the door 452 of the shutter unit 45 so asto block the communication between the interior of the second loadingchamber 42 and the interior of the working chamber 31 in the air tightcondition, and the second loading chamber 42 has been evacuated tovacuum.

[0268] As the shutter unit 46 closes the entrance and exit port 435, thesecond loading chamber is evacuated to vacuum again, so that a level ofthe vacuum in the second loading chamber may be higher than that in thefirst loading chamber. During this operation, the arm of the secondconveying unit 61 is rotated to a position where it can stretch towardthe stage unit 50 in the working chamber 31. On the other hand, in thestage unit within the working chamber 31, the Y table 52 moves upward inFIG. 18 to a position where the centerline X₀-X₀ of the X table 53 isapproximately in alignment with the X-axis line X₁-X₁ crossing arotational axis line O₂-O₂ of the second conveying unit 63, and the Xtable 53 moves to a position closest to the left most location in FIG.18, and resultantly the stage unit stands by in this condition. As thesecond loading chamber is evacuated to vacuum at approximately samelevel as the vacuum environment in the working chamber, the door 452 ofthe shutter unit 45 moves thus to open the entrance and exit ports 437,325, and the arm stretches with the tip portion holding the waferapproaching the stage unit within the working chamber 31. Then, it loadsthe wafer on the loading face 551 of the stage unit 50. As the loadingof the wafer has been completed, the arm is retracted and the shutterunit 45 closes the entrance and exit ports 437, 325.

[0269] The above explanation has been made to the operations to be takenuntil the wafer within the cassette c is finally placed on the stageunit, and when the wafer which has been loaded on the stage unit andfinished with the processing is to be returned back into the cassette c,the same operation but in the reverse sequence with respect to the abovedescription would be conducted. Further, since a plurality of wafers isloaded in the wafer rack 47, while the second conveying unit conveying awafer between the wafer rack and the stage unit, the first conveyingunit can convey another wafer between the cassette and the wafer rack,thereby allowing the inspection process to be performed efficiently.

[0270] In specific, if there are a wafer A which has been alreadyprocessed and a wafer B which has not yet processed in the wafer rack 47of the second conveying unit, the operation may be conducted accordingto the following procedure.

[0271] (1) At first, the wafer B which has not yet processed istransferred to the stage unit 50 and the processing is started.

[0272] (2) During this processing, the wafer A which has been processedis transferred from the stage unit 50 to the wafer rack 4 by the arm,and the wafer C which has not yet processed is withdrawn from the waferrack similarly by the arm and, after having been positioned by thepre-aligner, is moved to the wafer rack 47 of the loading chamber 41.This procedure allows the wafer A, which has been processed, to bereplaced by the wafer C, which has not yet processed, in the wafer rack47 during the wafer B being processed.

[0273] Further, a plurality of stage unit 50 may be arranged in parallelin dependence on the application of the apparatus for performing aninspection and evaluation, and in that case a plurality of wafers may beprocessed equally by transferring the wafers from one wafer racks 47 torespective units.

[0274]FIGS. 22 and 23 show alternative embodiment of supporting systemsof the main housing. In the alternative embodiment shown in FIG. 22, ahousing supporting unit 33 a is made of thick rectangular steel plate331 a, and a housing main body 32 a is mounted on that steel plate.Accordingly a bottom wall 321 a of the housing main body 32 a has muchthinner structure as compared to the bottom wall in the precedingembodiment. In another alternative embodiment shown in FIG. 23, ahousing main body 32 b and a loader housing 40 b are suspended and thussupported by a frame structure 336 b of a housing supporting unit 33 b.Lower end portions of a plurality of longitudinal frames 337 b fixedlyattached to the frame structure 336 b are secured to the bottom wall 321b of the housing main body 32 b in four corners thereof, and this designallows the bottom wall to support side walls and a top wall. A vibrationisolating unit 37 b is arranged between the frame structure 336 b and atable frame 36 b. Further, a loader housing 40 is also suspended by asuspender member 49 b secured to the frame structure 336. In the housingmain body 32 b of this alternative embodiment shown in FIG. 23, sincethe method of suspending type has been employed, the low center ofgravity may be accomplished for the whole unit consisting of the mainhousing and those variety of devices arranged inside thereof. Accordingto the present supporting system of the main housing and the loaderhousing including the alternative systems described above, the system isdesigned so as to prevent the vibration from the floor from beingtransmitted to the main housing and the loader housing.

[0275] In still another alternative embodiment, through not shown, onlythe housing main body of the main housing may be supported by thesupport unit from under side but the loader housing may be located onthe floor in the same method used for the adjacent mini-environmentdevice. Further, yet another alternative embodiment, though not shown,only the housing main body of the main housing may be supported by theframe structure by way of the suspending method but the loader housingmay be located on the floor in the same method used for the adjacentmini-environment device.

[0276] The electron optical unit 70 may use an electron beam apparatusof the image projection type shown in FIG. 1. In an alternativeembodiment, another electron beam apparatus of the image projection typeshown in FIG. 24 may be used. The electron beam apparatus of the imageprojection type as shown schematically in FIG. 24 comprises an electronoptical column 71 secured to a housing main body 32, and the electronoptical column 71 contains inside thereof an electron optical systemconsisting of a primary electron optical system (hereafter referred toas a primary optical system for simplicity) 72 and a secondary electronoptical system (hereafter referred to as a secondary optical system forsimplicity) 74, and a detecting system 76. The primary optical system 72is such an optical system that radiates an electron beam onto a topsurface of a wafer W to be inspected, and comprises an electron gun 721for emitting an electron beam, a lens system 727 consisting of anelectrostatic lens for converging the primary electron beam emitted fromthe electron gun 721, an E x B separator 723, and an objective lenssystem 724, each being arranged sequentially in this order placing theelectron gun 721 in the topmost level as shown in FIG. 24. The objectivelens system 724 of this embodiment is a decelerating electric field typeobjective lens. In this embodiment, an optical axis of the primaryelectron beam emitted from the electron gun 721 is inclined with respectto an irradiation optical axis along which the primary electron beam isradiated onto the wafer to be inspected (perpendicular to the surface ofthe wafer). An electrode 725 is arranged between the objective lenssystem 724 and the wafer W to be inspected. This electrode 725 is formedto be axially symmetrical with respect to the irradiation optical axisof the primary electron beam and a voltage applied to this electrode iscontrolled by a power supply 726.

[0277] The secondary optical system 74 comprises a lens system 741consisting of an electrostatic lens for passing therethrough secondaryelectrons separated from the primary optical system by the E x B typedeflector 723. This lens system 741 functions as a magnifying lens formagnifying a secondary electron image.

[0278] The detecting system 76 comprises a detector 761 disposed in animage forming plane for the lens system 741 and an image processingsection 763.

[0279] An operation of the electron optical unit 70 having aconfiguration described above will now be described.

[0280] The primary electron beam emitted from the electron gun 721 isconverged by the lens system 722. The converged electron beam enters tothe E x B type deflector 723, which deflects the beam so as to beradiated onto the surface of the wafer W at a right angle, and then bythe objective lens system 724, the beam is formed into an image on thesurface of the wafer W.

[0281] The secondary electrons emitted from the wafer by the irradiationof the primary electron beam are accelerated by the objective lenssystem 724, and the accelerated secondary electrons are entered into theE x B type deflector 723, advanced straight ahead through the E x B typedeflector and guided by a lens system 741 of the secondary opticalsystem to a detector 761. Then, the detector 761 detects the secondaryelectrons and sends that detection signal to the image processingsection 763.

[0282] It is assumed in this embodiment that a voltage as high as 10 to20 kV is applied to the objective lens system 724 and the wafer 27 isgrounded.

[0283] Then, in the case where the wafer W included a via “b” and thevoltage of −200 V was applied to the electrode 725, the resultingelectric field in the electron beam irradiation plane of the wafer wasobserved to be within the range from 0 to −0.1 V/mm (“−” indicates thatthe wafer W has a higher potential). In this condition, although thedefect inspection of the wafer W was conducted without any electricdischarge occurring between the objective lens system 724 and the waferW, a detection efficiency for the secondary electron was somewhatdecreased. For this reason, a series of operations comprising theirradiation of the electron beam and the detection of the secondaryelectrons was repeated, for example, four times, and the obtaineddetection results were processed with the accumulative addition oraveraging operation, so that a predetermined detection sensitivity wasobtained.

[0284] Further, even in the case where the wafer W included no via “b”and the voltage of +350 V was applied to the electrode 725, the defectinspection of the wafer W was successfully conducted without anyelectric discharge occurring between the objective lens system 724 andthe wafer W. In this case, since the secondary electrons were convergedby the voltage applied to the electrode 725 and further converged by theobjective lens system 724, the detection efficiency of the secondaryelectrons at the detector 761 was thus improved. Accordingly, theprocessing speed achieved by the apparatus in serving as a wafer defectinspection apparatus was also increased, and the inspection wasperformed with a higher throughput.

[0285] The pre-charge unit 81 has been installed within the workingchamber 31 at a location adjacent to the electron optical column 71 ofthe electron optical unit 70, as shown in FIG. 17. Since the inspectionapparatus of the present invention is such type of apparatus thatinspects a device pattern or the like formed on a surface of a substrateor a wafer subject to an inspection by irradiating an electron beam onand scanning thereby the surface thereof, wherein data of the secondaryelectrons generated by the irradiation of the electron beam is used asthe data of the wafer surface, there is a fear that the surface of thewafer could be charged up depending on the condition of the material ofthe wafer, the energy of the radiated electron and so on. Also, there isa possibility that some locations on the surface of the wafer may becharged up to a high degree and some locations on the surface of thewafer may be charged up to a low degree. Unevenness in an amount ofcharge-up on the surface of the wafer may lead to unevenness in thesecondary image data and prohibit acquisition of accurate data. Fromthis viewpoint, this embodiment has employed the pre-charge unit 81having a charged particle irradiation section 811 in order to preventthis unevenness in charge-up. In order to eliminate the unevenness incharge-up, before the scanning electron beam is radiated onto apredetermined spot on the wafer to be inspected, the charged particlesare radiated onto the surface from the charged particle irradiationsection 811 of the pre-charge unit, thereby eliminating the unevennessin charge-up. The charge-up on the surface of the wafer may be detectedby forming in advance an image of the surface of the wafer subject tothe inspection and then evaluating that image, and the pre-charge unit81 may be operated based on that detection result.

[0286] Further, with this pre-charge unit, the primary electron beam maybe defocused upon irradiation.

[0287] In FIG. 25, a potential applying mechanism 83 is to control thegeneration of the secondary electrons by applying the potential of +/− afew V to an apron of the stage, on which a wafer is loaded, based on thefact that the data for the secondary electrons emitted from the wafer (arate of secondary electron generation) depends on the potential of thewafer. Further, this potential applying mechanism also plays a role fordecelerating an energy originally pertained to the emitted electron soas to make an irradiation electron energy on the order of 100 to 500 eVonto the wafer.

[0288] The potential applying mechanism 83, as shown in FIG. 25,comprises a voltage applying unit 831 having an electric contact with aloading face 541 of the stage 50 and a charge-up investigation andvoltage determination system (hereafter referred to as an investigationand determination system) 832. The investigation and determinationsystem 832 comprises a monitor 833 having an electric contact with animage forming section 763 of the detecting system 76 of the electronoptical unit 70, an operator console 834 connected to the monitor 833,and a CPU 835 connected to the operator console 834. The CPU 835 hasbeen designed so as to supply a signal to said voltage applying unit831.

[0289] This potential applying mechanism has been designed so as tosearch for a potential with which the wafer subject to inspection ishardly charged up and apply that potential to the apron of the stage.

[0290] Referring to FIG. 26, an electron beam calibration mechanism 85comprises a plurality of Faraday cups 851 and another plurality ofFaraday cups 852, each for measuring a beam current and being arrangedat a plurality of locations in a side portion of the wafer loading face541 on the turn table described above. The Faraday cups 851 are designedfor a thin beam (about +2 μm) and the Faraday cups 852 are designed fora thick beam (about φ30 μm). The Faraday cups 851 for the thin beammeasure a beam profile by a step-forwarding of the turn table, while theFaraday cups 852 for the thick beam measure a total current volume ofthe beam. Those sets of Faraday cups 851 and 852 have been arranged suchthat the level of the top surfaces thereof are in flash with the levelof the top surface of the wafer W loaded on the loading face 541. Withsuch arrangements, the primary electron beam emitted from the electrongun may be monitored regularly. This is because the electron gun may notalways emit an electron beam of constant quantity but the emissionquantity of the beam may vary over operation time.

[0291] An alignment control unit 87 shown in FIG. 27 is a unit forpositioning the wafer W with respect to the electron optical unit 70 byusing the stage unit 50 and it allows for a control operation includinga rough alignment of the wafer by way of a wide field observation usingan optical microscope 871 (a measurement with a lower magnification thanthe electron optical system), an alignment with a higher magnificationby using the electron optical system of the electron optical unit 70, afocal tuning, a setting of an inspection region, a pattern alignment andso on. The reason why the optical system is used to inspect the waferwith the lower magnification in such a manner as described above is thatthe automatic inspection of the pattern on the wafer requires that thealignment mark should be easily detected by the electron beam when thepattern of the wafer is observed in a narrow field by using the electronbeam thus to perform the wafer alignment.

[0292] An optical microscope 871 is arranged in the housing (may bearranged so as to be movable within the housing), and a light source foractuating the optical microscope may be also arranged within thehousing, though not shown. Further, the electron optical system used forthe observation with the high magnification may be the electron opticalsystem (the primary optical system 72 and the secondary optical system74) of the electron optical unit 70, which will be used in common. Theconfiguration thereof, if illustrated schematically, may be shown, forexample, by FIG. 27. To observe a point on the wafer subject toobservation with a low magnification, the X stage 53 of the stage unit50 is moved in the X direction to bring the point on the wafer subjectto the observation into a field of the optical microscope. After thevisual recognition of the wafer in the wide field by using the opticalmicroscope, the point to be observed on the wafer is displayed on amonitor 873 via a CCD 872 and the point to be observed is roughlydetermined. In that case, the magnification applied to the opticalmicroscope may be changed gradually from the lower scale to the higherscale.

[0293] Then, the stage 50 is moved by a distance equivalent to aninterval δx between an optical axis of the electron optical unit 70 andan optical axis of the optical microscope 871 thus to place the point tobe observed on the wafer, which has been determined in advance by theoptical microscope, in a field position of the electron optical unit. Inthat case, since the interval δx between the optical axis O₃-O₃ of theelectron optical unit 70 and the optical axis O₄-O₄ of the opticalmicroscope 871 has been known in advance (in this embodiment, it isassumed that the optical axes are displaced from each other only in thedirection along the X-axis line, but they may be displaced in the X-axisdirection and the Y-axis direction at the same time), the movementcorresponding to the value of δx can bring the point to be observed intothe visually recognizable location. After the movement of the point tobe observed to the visually recognizable location of the electronoptical unit having been completed, the electron optical system performsthe SEM image taking of the point to be observed with a highmagnification, and the obtained image will be stored or displayed on themonitor 765 via the CCD 761.

[0294] In this way, after the observed point on the wafer having beendisplayed on the monitor by the electron optical system with the highmagnification, a displacement of the wafer in the rotational directionwith respect to the rotation center of the turn table 54 of the stageunit 50, i.e., the displacement δθ of the wafer in the rotationaldirection around the optical axis O₃-O₃ of the electron optical systemis detected by a known method, and also the displacements of apredetermined pattern in the X-axis and the Y-axis directions isdetected with respect to the electron optical unit. Then, based on thedetected values and separately obtained data for an inspection markgiven to the wafer or data regarding a geometry of the pattern on thewafer or the like, the operation of the stage unit 50 is controlled soas to adjust the alignment of the wafer.

[0295] According to the sixth embodiment, the following effects may beobtained.

[0296] (A) An overall configuration for the inspection apparatus of theimage projection type using the electron beam can be obtained, andthereby an objective sample to the inspection can be processed with highthroughput.

[0297] (B) Since the clean air flow is applied to the objective materialto be inspected within the mini-environmental space so as to prevent thedeposition of dust to the material and also the sensor is provided forobserving a level of cleanness, the objective sample to the inspectioncan be inspected while monitoring the dust within the space.

[0298] (C) Since the loading chamber and the working chamber aresupported as one unit by a vibration isolating unit, the supply of theobjective material to be inspected into the stage unit and theinspection thereof can be carried out without any affection from theouter environment.

[0299] (D) Since the pre-charge unit has been provided, even a wafermade of insulating material may be hardly affected by the charge-up.

(Seventh Embodiment)

[0300] A seventh embodiment relates to an improvement of the stage.Prior to the explanation of this embodiment, a stage according to theprior art will be described.

[0301] A stage for accurately positioning a sample in a vacuumatmosphere has been used in an apparatus in which a charged particlebeam such as an electron beam is radiated onto a surface of a samplesuch as a semiconductor wafer so as to expose the surface of the sampleto a pattern of a semiconductor circuit or the like, or so as to inspecta pattern formed on the surface of the sample, and also in anotherapparatus in which the charged particle beam is radiated onto the sampleso as to apply an ultra-precise processing thereto.

[0302] When said stage is required to be positioned highly accurately,one structure has been conventionally employed, in which the stage issupported in non-contact manner by a hydrostatic bearing. In this case,the vacuum level in a vacuum chamber is maintained by forming in anextent of the hydrostatic bearing a differential pumping mechanism forexhausting a high pressure gas so that the high pressure gas suppliedfrom the hydrostatic bearing may not be directly exhausted into thevacuum chamber.

[0303]FIG. 29 shows one of the examples of such stage according to theprior art. In the configuration of FIG. 29, a tip portion of an electronoptical column 1-7 or a charged particle beam irradiating section 2-7 ofa charged particle beam apparatus for generating a charged particle beamand irradiating it onto a sample is attached to a housing 8-7 whichdefines a vacuum chamber C. An interior of the electron optical columnis exhausted to vacuum through a vacuum pipe 10-7 and so as the chamberC through a vacuum pipe 11-7. Herein, the charged particle beam isradiated from the tip portion 2-7 of the electron optical column 1-7onto a sample S such as a wafer or the like placed thereunder.

[0304] The sample S is detachably held on a sample table 4-7 by a knownmanner, and the sample table 4-7 is mounted on an upper face of a Ydirectionally movable section 5-7 of an XY stage (hereafter, referred toas a stage for simplicity) 3-7. The above-mentioned Y directionallymovable section 5-7 is equipped with a plurality of hydrostatic bearings9-7 attached on respective planes facing to respective guide planes 6a-7 of an X directionally movable section 6-7 of the stage 3-7 (on bothof the right and left faces and also on a bottom face in FIG. 29[A]), sothat the section 5-7 may be moved in the Y direction (lateral directionin FIG. 29[B]) while keeping a micro gap formed between the guide planesand said respective planes facing thereto owing to an operation of saidhydrostatic bearings 9-7. Further, a differential pumping mechanism isprovided surrounding the hydrostatic bearing so that the high-pressuregas supplied to the hydrostatic bearing might not leak into the vacuumchamber C. This configuration is shown in FIG. 30. Doubled grooves 18-7and 17-7 are formed surrounding the hydrostatic bearings 9-7, and thesegrooves are regularly exhausted to vacuum through a vacuum pipe by avacuum pump, though not shown. Owing to such structure, the Ydirectionally movable section 5-7 is allowed to move freely in the Ydirection in the vacuum atmosphere as supported in non-contact manner.Those doubled grooves 18-7 and 17-7 are formed in a plane of the movablesection 5-7 on which the hydrostatic bearing 9-7 is arranged, so as tocircumscribe said hydrostatic bearing. It is to be noticed that thestructure of the hydrostatic bearing may be any conventional one and itsdetailed description will be omitted.

[0305] The X directionally movable section 6-7 on which said Ydirectionally movable section 5-7 is mounted is formed to be concave inshape with the top face opened, as obviously seen from FIG. 29, and saidX directionally movable section 6-7 is also provided with completelysimilar hydrostatic bearings and grooves, so that the section 6-7 may besupported in the non-contact manner with respect to the stage table 7-7so as to be movable freely in the X direction.

[0306] Combining said Y directionally movable section 5-7 with the Xdirectionally movable section 6-7 allows the sample S to be moved to adesired position in the horizontal direction relative to the tip portionof the electron optical column or the charged particle beam irradiatingsection 2-7, so that the charged particle beam can be radiated to adesired location of the sample.

[0307] With the stage including a combination of the hydrostatic bearingand the differential pumping mechanism as described above, the guideplane 6 a-7 or 7 a-7 facing to the hydrostatic bearing 9-7 makes areciprocating motion between a high-pressure atmosphere in thehydrostatic bearing portion and a vacuum environment within the chamberwhile the stage moves. During this reciprocating motion, such a gassupply cycle is repeated in which while the guide plane being exposed tothe high-pressure atmosphere, the gas is adsorbed onto the guide plane,and upon being exposed to the vacuum environment, the adsorbed gas isdesorbed into the environment. Because of this gas supply cycle, everytime when the stage moves, there has occurred such an event that thevacuum level in the chamber C is degraded, which has caused suchproblems that the exposure, inspection, or processing with the chargedparticle beam described above could not be carried out stably, and thesample might be contaminated.

[0308] Now, referring to the attached drawings, an embodiment of anelectron beam apparatus according to the seventh embodiment of thepresent invention, which has been made in order to solve the aboveproblems, will be described. It is to be noted that the same referencenumerals are used to designate the same components in common to both ofthe embodiment according to the prior art shown in FIG. 29 and aplurality of embodiments of the present invention.

[0309]FIG. 31 shows a first mode for carrying out the seventhembodiment.

[0310] A division plate 14-7 is attached onto an upper face of the Ydirectionally movable section 5-7 of the stage 3, wherein said divisionplate 14-7- overhangs to a great degree approximately horizontally inthe +Y direction and the −Y direction (the lateral direction in FIG.31[B]), so that between an upper face of the X directionally movablesection 6-7 and the division plate 14-7 may be always provided a narrowgap 50-7 with small conductance therebetween. Also, a similar divisionplate 12-7 is attached onto the upper face of the X directionallymovable section 6-7 so as to overhang in the +/−X direction (the lateraldirection in FIG. 31[A]), so that a narrow gap 51-7 may be constantlyformed between an upper face of a stage table 7-7 and said divisionplate 12-7. The stage table 7-7 is fixedly secured onto a bottom wallwithin a housing 87 with a known method.

[0311] In this way, since the narrow gap 50-7 and 51-7 are constantlyformed wherever the sample table 4-7 may move to, and the gaps 50-7 and51-7 can prevent the movement of a discharged gas even if a gas isdischarged or leaked along the guide plane 6 a-7 or 7 a-7 upon movementof the movable sections 5-7 or 6-7, a pressure increase can be regulatedto significantly low level in a space 24-7 adjacent to the sample towhich the charged particle beam is radiated.

[0312] Since in a side face and an under face of the movable section 3-7and also in an under face of the movable section 6-7 of the stage, thereare provided grooves for differential pumping formed surroundinghydrostatic bearings 9-7, as shown in FIG. 30, and accordingly spacesnearby there grooves are exhausted to vacuum through those grooves,therefore in a case where narrow gaps 50-7 and 51-7 have been formed,the discharged gas from the guiding planes is mainly evacuated by thosedifferential pumping sections. Owing to this, the pressure in thosespaces 13-7 and 15-7 within the stage are kept to be higher level thanthe pressure within a chamber C. Accordingly, if there are more portionsprovided for vacuum pumping the spaces 13-7 and 15-7 in addition to thedifferential pumping grooves 17-7 and 18-7, the pressure within thespaces 13-7 and 15-7 can be decreased, and the pressure rise of thespace 24-7 in the vicinity of the sample can be controlled to be furtherlow. For this purpose, vacuum pumping channels 11-1-7 and 11-2-7 areprovided. The vacuum pumping channel 11-1-7 extends through the stagetable 7-7 and the housing 8-7 to communicate with the outside of thehousing 8. On the other hand, the pumping channel 11-2-7 is formed inthe X directionally movable section 6-7 and opened in an under facethereof.

[0313] It is to be noted that though arranging the division plates 12-7and 14-7 might cause a problem requiring the chamber C to be extended soas not to interfere with the division plates, this can be improved byemploying those division plates of stretchable material or structure.There may be suggested one embodiment in this regard, which employs thedivision plates made of rubber or in a form of bellows, and the endsportions thereof in the direction of movement are fixedly securedrespectively, so that each end of the division plate 14-7 is secured tothe X directionally movable section 6-7 and that of the division plate12-7 to the inner wall of the housing 8-7.

[0314]FIG. 32 shows a second mode for carrying out this embodiment.

[0315] In this embodiment, a cylindrical divider 16-7 is disposedsurrounding the tip portion of the electron optical column or thecharged particle beam irradiating section 2-7, so that a narrow gap maybe produced between an upper face of a sample S and the cylindricaldivider 16-7. In such configuration, even if the gas is discharged fromthe XY stage to increase the pressure within the chamber C, since aspace 24-7 within the divider has been isolated by the divider 16-7 andexhausted with a vacuum pipe 10-7, there could be generated a pressuredeference between the pressure in the chamber C and that in the space24-7 within the divider, thus to control the pressure rise in the space24-7 within the divider to be low. Preferably, the gap between thedivider 16-7 and the sample surface should be approximately some ten μmto some mm, depending on the pressure level to be maintained within thechamber C and in the surrounding of the irradiating section 2-7. It isto be understood that the interior of the divider 16-7 is made tocommunicate with the vacuum pipe by the known method.

[0316] On the other hand, the charged particle beam irradiationapparatus may sometimes apply a high voltage of about some kV to thesample S, and so it is feared that any conductive materials locatedadjacent to the sample could cause an electric discharge. In this case,the divider 16-7 made of insulating material such as ceramic may be usedin order to prevent any discharge between the sample S and the divider16-7.

[0317] It is to be noted that a ring member 4-1-7 arranged so as tosurround the sample S (a wafer) is a plate-like adjusting part fixedlyattached to the sample table 4-7 and set to have the same height withthe wafer so that a micro gap 52-7 may be formed throughout a fullcircle of the tip portion of the divider 16-7 even in a case of thecharged particle beam being radiated onto an edge portion of the samplesuch as the wafer. Thereby, whichever location on the sample S may beirradiated by the charged particle beam, the constant micro gap 52-7 canbe always formed in the tip portion of the divider 16-7 so as tomaintain the pressure stable in the space 24-7 surrounding the electronoptical column tip portion.

[0318] Further, FIG. 33 shows a third mode for carrying out the seventhembodiment.

[0319] A divider 19-7 having a differential pumping structure integratedtherein is arranged so as to surround the charged particle beamirradiating section 2-7 of an electron optical column 1-7. The divider19-7 is cylindrical in shape and has a circular channel 20-7 formedinside thereof and an exhausting path 21-7 extending upwardly from saidcircular channel 20-7. Said exhausting path 21-7 is connected to avacuum pipe 23-7 via an inner space 22-7. A micro space as narrow asdozens of μm to few mm is formed between the lower end of the divider19-7 and the upper face of the sample S.

[0320] With such configuration as described above, even if the gas isdischarged from the stage in association with the movement of the stageresulting in an increase of the pressure within the chamber C, andeventually is to possibly flow into the space of tip portion or thecharged particle beam irradiating section 2-7, the gas is blocked toflow in by the divider 19-7, which has reduced the gap between thesample S and itself so as to make the conductance very low, thus toreduce the flow-in rate. Further, since any gas that has flown into isallowed to be exhausted through the circular channel 20-7 to the vacuumpipe 23-7, there will be almost no gas remained to flow into the space24-7 surrounding the charged particle beam irradiating section 2-7, andaccordingly the pressure of the space surrounding the charged particlebeam irradiating section 2-7 can be maintained to be a desired highvacuum level.

[0321]FIG. 34 shows a fourth mode for carrying out the seventhembodiment.

[0322] A divider 26-7 is arranged so as to surround the charged particlebeam irradiating section 2-7 in the chamber C and accordingly to isolatethe charged particle beam irradiating section 2-7 from the chamber C.This divider 26-7 is coupled to a refrigerating machine 30-7 via asupport member 29-7 made of material of high thermal conductivity suchas copper or aluminum, and is kept as cool as −100° C. to −200° C. Amember 27-7 is provided for blocking a thermal conduction between thecooled divider 26-7 and the electron optical column and is made ofmaterial of low thermal conductivity such as ceramic, resin or the like.Further, a member 28-7 is made of insulating material such as ceramic orthe like and is attached to the lower end of the divider 26-7 so as toprevent any electric discharge between the sample S and the divider26-7.

[0323] With such configuration as described above, any gas moleculesattempting to flow into the space surrounding the charged particle beamirradiating section from the chamber C are blocked by the divider 26-7,and even if there are any molecules successfully flown into the section,they are frozen to be trapped on the surface of the divider 26-7, thusallowing the pressure in the space 24-7 surrounding the charged particlebeam irradiating section to be kept low.

[0324] It is to be noted that a variety type of refrigerating machinesmay be used for the refrigerating machine in this embodiment, forexample, a cooling machine using liquid nitrogen, a He refrigeratingmachine, a pulse-tube type refrigerating machine or the like.

[0325]FIG. 35 shows a fifth mode for carrying out the seventhembodiment.

[0326] The division plates 12-7 and 14-7 are respectively arranged onboth of the movable sections of the stage 3-7 similarly to thoseillustrated in FIG. 31, and thereby, if the sample table 4-7 is moved toany locations, the space 13-7 within the stage is separated from theinner space of the chamber C by those division plates via the narrowgaps 50-7 and 51-7. Further, another divider 16-7 similar to that asillustrated in FIG. 32 is formed surrounding the charged particle beamirradiating section 2-7 so as to separate a space 24-7 accommodating thecharged particle beam irradiating section 2-7 therein from the interiorof the chamber C with a narrow gap 52-7 disposed therebetween. Owing tothis, upon movement of the stage, even if the gas having been adsorbedon the stage is discharged into the space 13-7 to increase the pressurein this space, the pressure increase in the chamber C is kept to be low,and the pressure increase in the space 24-7 is also kept to be muchlower. This allows the pressure in the space 24-7 for irradiating thecharged particle beam to be maintained at low level. Alternatively,employing the divider 19-7 having the differential pumping mechanismintegrated therein as explained with reference to the divider 16-7, orthe divider 26-7 cooled with the refrigerating machine as shown in FIG.33 allows the space 24-7 to be maintained stably with further loweredpressure.

[0327] The electron beam apparatus to be installed in the electronoptical column 1-7 may employ any optical system and detector asdesired. For example, either of the image projection type shown in FIG.1 and the like or the scanning type shown in FIG. 41 and the like may beemployable.

[0328] According to the seventh embodiment of the present invention, thefollowing effects may be brought about.

[0329] (A) The stage unit can bring out a good performance of accuratepositioning within vacuum atmosphere, and further the pressure in thespace surrounding the charged particle beam irradiating location ishardly increased. That is, this allows the charged particle beamprocessing to be applied to the sample with high accuracy.

[0330] (B) The gas discharged or leaked from the hydrostatic bearinghardly goes though the divider and reaches to the space for the chargedparticle beam irradiating system. Thereby, the vacuum level in the spacesurrounding the charged particle beam irradiating location can befurther stabilized.

[0331] (C) The desorbed gas hardly goes through to the space for thecharged particle beam irradiating system, and it is facilitated tomaintain the vacuum level in the space surrounding the charged particlebeam irradiating region stable.

[0332] (D) The interior of the vacuum chamber is partitioned into threechambers, i.e., a charged particle beam irradiation chamber, ahydrostatic bearing chamber, and an intermediate chamber, whichcommunicate with each other via a small conductance. Further, the vacuumpumping system is constructed to control the pressures in the respectivechambers sequentially, so that the pressure in the charged particle beamirradiation chamber is the lowest, the intermediate chamber medium, andthe hydrostatic bearing chamber the highest. The pressure fluctuation inthe intermediate chamber can be reduced by the divider, and the pressurefluctuation in the charged particle beam irradiation chamber can befurther reduced by another step of divider, so that the pressurefluctuation therein can be reduced substantially to a non-problematiclevel.

[0333] (E) According to the first mode for carrying out the seventhembodiment, the pressure increase upon movement of the stage can becontrolled to be low.

[0334] (F) According to the second mode for carrying out the seventhembodiment, the pressure increase upon movement of the stage can befurther controlled to be lower.

[0335] (G) According to the third mode for carrying out the seventhembodiment, since the defect inspection apparatus with highly accuratestage positioning performance and with a stable vacuum level in thecharged particle beam irradiating region can be accomplished, theinspection apparatus with high inspection performance and without anyfear of contamination of the sample can be provided.

[0336] (H) According to the fourth mode for carrying out the seventhembodiment, since an exposure apparatus with highly accurate stagepositioning performance and with a stable vacuum level in the chargedparticle beam irradiating region can be accomplished, the exposureapparatus with high exposing accuracy and without any fear ofcontamination of the sample can be provided.

[0337] (I) According to the fifth mode for carrying out the seventh,manufacturing the semiconductor by using the apparatus with highlyaccurate stage positioning performance and with a stable vacuum level inthe charged particle beam irradiating region allows to form aminiaturized micro semiconductor circuit.

(Eighth Embodiment)

[0338] An eighth embodiment relates to an improvement of the stage.Prior to explaining this embodiment, a stage according to the prior artwill be described.

[0339]FIG. 36 shows an example of the stage according to the prior artsimilarly to the seventh embodiment. In the configuration of FIG. 36, atip portion of an electron optical column 1-8 or a charged particle beamirradiating section 2-8 of a charged particle beam apparatus forgenerating a charged particle beam and irradiating it onto a sample isattached to a housing 14′-8 which defines a vacuum chamber C. Theinterior of the electron optical column is exhausted to vacuum through avacuum pipe 18-8 and so as the chamber C through a vacuum pipe 19′-8.Herein, the charged particle beam is radiated from the tip portion 2-8of the electron optical column 1-8 onto a sample S such as a wafer orthe like placed thereunder.

[0340] The sample S is detachably held on a sample table “t” in a knownmanner, and the sample table t is mounted on an upper face of a Ydirectionally movable section 4′-8 of an XY stage (hereafter, referredto as a stage for simplicity) 3′-8. The above-mentioned Y directionallymovable section 4′-8 is equipped with a plurality of hydrostaticbearings 9′-8 attached on respective planes facing to respective guideplanes 5 a′-8 of an X directionally movable section 5′-8 of the stage3-8 (on both of the right and left faces and also on a bottom face inFIG. 36[A]), so that the section 4′-8 may be moved in the Y direction(lateral direction in FIG. 36[B]) while keeping a micro gap formedbetween the guide planes and said respective planes facing thereto owingto an operation of said hydrostatic bearings 9′-8. Further, adifferential pumping mechanism is provided surrounding the hydrostaticbearing so that a high-pressure gas supplied to the hydrostatic bearingmight not leak into the vacuum chamber C. This is shown in FIG. 37.Doubled grooves g1 and g2 are formed surrounding the hydrostaticbearings 9′-8, and these grooves are regularly exhausted to vacuumthrough a vacuum pipe by a vacuum pump, though not shown. Owing to suchstructure, the Y directionally movable section 4′-8 is allowed to movefreely in the Y direction in the vacuum atmosphere as supported in thenon-contact manner. Those doubled grooves g1 and g2 are formed in aplane of the movable section 4′-8 on which the hydrostatic bearing 9′-8is arranged, so as to circumscribe said hydrostatic bearing. It is to benoticed that the structure of the hydrostatic bearing may be anyconventional one and its detailed description will be omitted.

[0341] The X directionally movable section 5′-8 on which said Ydirectionally movable section 4′-8 is mounted is formed to be concave inshape with the top face opened, as obviously seen from FIG. 36, and saidX directionally movable section 5′-8 is also provided with completelysimilar hydrostatic bearings and grooves, so that the section 5′-8 maybe supported in a non-contact manner with respect to the stage table6′-8 so as to be movable freely in the X direction.

[0342] Combining said Y directionally movable section 4′-8 with the Xdirectionally movable section 5′-8 allows the sample S to be moved to adesired position in the horizontal direction relative to the tip portionof the electron optical column or the charged particle beam irradiatingsection 2-8, so that the charged particle beam can be radiated to adesired location of the sample.

[0343] However, there have been such problems in the above-describedstage including a combination of the hydrostatic bearing and thedifferential pumping mechanism that because of the differential pumpingmechanism having been added, the structure has become more complicatedand increased in size but the reliability as a stage has decreased incontrast with the increased cost as compared to a stage having ahydrostatic bearing used in the atmospheric pressure.

[0344] Now, referring to the attached drawings, a mode for implementingan electron beam apparatus according to the eighth embodiment of thepresent invention, which has been made to solve the above problems, willbe described. It is to be noted that the same reference numerals areused to designate the same components in common to both of theembodiment according to the prior art shown in FIG. 36 and therespective modes for implementing the eighth embodiment. It is also tobe appreciated that a term “vacuum” used in the content of thisspecification means a vacuum as referred to in this field of art.

[0345]FIG. 38 shows a first mode for carrying out the eighth embodimentof the present invention.

[0346] A tip portion of an electron optical column 1-8 or a chargedparticle beam irradiating section 2-8, which functions to radiate acharged particle beam onto a sample, is mounted to a housing 14-8defining a vacuum chamber C. The sample “S” loaded on an X directionallymovable table of an XY stage 3-8 (movable in the lateral direction inFIG. 38) is adapted to be positioned immediately under the electronoptical column 1-8. The XY stage 3-8 of high precision allows thecharged particle beam to be radiated onto this sample S accurately inany arbitrary location on the sample surface.

[0347] A pedestal 6-8 of the XY stage 3 is fixedly mounted on a bottomwall of the housing 14-8, and a Y table 5 movable in the Y direction(the vertical direction on page of FIG. 38) is mounted on the pedestal6-8. Convex portions are formed on both of opposite sidewall faces (theleft and the right side faces in FIG. 38) of the Y table 58respectively, each of which protrudes into a concave groove formed on aside surface facing to the Y table in either of a pair of Y-directionalguides 7 a-8 and 7 b-8 mounted on the pedestal 6-8. The concave grooveextends approximately along the full length of the Y directional guidein the Y direction. A top, a bottom and side faces of respective convexportions protruding into the grooves are provided with known hydrostaticbearings 11 a-8, 9 a-8, 11 b-8, and 9 b-8 respectively, through which ahigh-pressure gas is blown out and thereby the Y table 5-8 is supportedby the Y directional guides 7 a-8 and 7 b-8 in non-contact manner so asto be movable smoothly forth and back in the Y direction. Further, alinear motor 12-8 of known structure is arranged between the pedestal6-8 and the Y table 5-8 for driving the Y table 5 in the Y direction.The Y table is supplied with the high-pressure gas through a flexiblepipe 22-8 for supplying a high-pressure gas, and the high-pressure gasis further supplied to the above-described hydrostatic bearings 9 a-8 to11 a-8 and 9 b-8 to 11 b-8 though a gas passage (not shown) formedwithin the Y table. The high-pressure gas supplied to the hydrostaticbearings blows out into a gap of some microns to some ten microns formedrespectively between the bearings and the opposing guide planes of the Ydirectional guide so as to position the Y table accurately with respectto the guide planes in the X and Z directions (up and down directions inFIG. 38).

[0348] The X table 4-8 is mounted on the Y table so as to be movable inthe X direction (the lateral direction in FIG. 38). A pair of Xdirectional guides 8 a-8 and 8 b-8 (only 8 a-8 is illustrated) with thesame configuration as of the Y directional guides 7 a-8 and 7 b-8 isarranged on the Y table 5-8 with the X table 4-8 sandwichedtherebetween. Concave grooves are also formed in the X directionalguides on the sides facing to the X table and convex portions are formedon the side portions of the X table (side portions facing to the Xdirectional guides). The concave groove extends approximately along thefull length of the X directional guide. A top, a bottom and side facesof respective convex portions of the X table 4-8 protruding into theconcave grooves are provided with hydrostatic bearings (not shown)similar to those hydrostatic bearings 11 a-8, 9 a-8, 10 a-8, 11 b-8, 9b-8 and 10 b-8 in the similar arrangements. A linear motor 13-8 of knownconfiguration is disposed between the Y table 5-8 and the X table 4-8 soas to drive the X table in the X direction. Further, the X table 4-8 issupplied with a high-pressure gas through a flexible pipe 21-8, and thusthe high-pressure gas is supplied to the hydrostatic bearings. The Xtable 4-8 is supported highly precisely with respect to the Ydirectional guide in a non-contact manner by way of said high-pressuregas blowing out from the hydrostatic bearings to the guide planes of theX directional guides. The vacuum chamber C is exhausted through vacuumpipes 19-8, 20 a-8 and 20 b-8 coupled to a vacuum pump of knownstructure. Those pipes 20 a-8 and 20 b-8 penetrate through the pedestal6-8 to the top surface thereof to open their inlet sides (inner side ofthe vacuum chamber) in the proximity of the locations to which thehigh-pressure gas is ejected from the XY stage 3-8, so that the pressurein the vacuum chamber may be prevented to the utmost from rising up bythe blown-out gas from the hydrostatic bearings.

[0349] A differential pumping mechanism 25-8 is arranged so as tosurround the tip portion of the electron optical column 1-8 or thecharged particle beam irradiating section 2-8, so that the pressure in acharged particle beam irradiation space 30-8 can be controlled to besufficiently low even if there exists high pressure in the vacuumchamber C. That is to say, an annular member 26-8 of the differentialpumping mechanism 25-8 mounted so as to surround the charged particlebeam irradiating section 2-8 is positioned with respect to the housing14-8 so that a micro gap (in a range of some microns to some-hundredmicrons) 40-8 can be formed between the lower face thereof (the surfacefacing to the sample) and the sample, and an annular groove 27-8 isformed in the lower face thereof. That annular groove 27-8 is coupled toa vacuum pump or the like, though not shown, through an exhausting pipe28-8. Accordingly, the micro gap 40-8 can be exhausted through theannular groove 27-8 and the exhausting pipe 28-8, and if any gaseousmolecules from the chamber C attempt to enter the space 30-8circumscribed by the annular member 26-8, they may be exhausted.Thereby, the pressure within the charged particle beam irradiation space30-8 can be maintained to be low and thus the charged particle beam canbe radiated without any troubles.

[0350] That annular groove may be made doubled or tripled, depending onthe pressure in the chamber C and the pressure within the chargedparticle beam irradiation space 30-8.

[0351] Typically, dry nitrogen is used as the high-pressure gas to besupplied to the hydrostatic bearings. If available, however, a muchhigher-purity inert gas should be preferably used instead. This isbecause any impurities, such as water contents or oil and fat contents,included in the gas could stick on the inner surface of the housingdefining the vacuum chamber or on the surfaces of the stage componentsleading to the deterioration in vacuum level, or could stick on thesample surface leading to the deterioration in vacuum level in thecharged particle beam irradiation space.

[0352] It should be appreciated that though typically the sample S isnot placed directly on the X table, but may be placed on a sample tablehaving a function to detachably carry the sample and/or a function tomake a fine tuning of the position of the sample relative to the XYstage 3-8, an explanation thereof is omitted in the above descriptionfor simplicity due to the reason that the presence and structure of thesample table has no concern with the principal concept of the presentinvention.

[0353] Since a stage mechanism of a hydrostatic bearing used in theatmospheric pressure can be used in the above-described charged particlebeam apparatus mostly as it is, a stage having an equivalent level ofprecision with equivalent cost and size to those of the stage ofhigh-precision fitted for a use in the atmospheric pressure, which istypically used in an exposure apparatus or the likes, may beaccomplished for an XY stage to be used in a charged particle beamapparatus.

[0354] It should be also appreciated that the configuration andarrangement of the hydrostatic guide and the actuator (the linear motor)have been only illustratively explained in the above description, andany hydrostatic guides and actuators usable in the atmospheric pressuremay be applicable.

[0355]FIG. 39 shows an example of numeric values representative of thesizes of the annular member 26-8 and the annular groove formed in theannular member 26-8 of the differential pumping mechanism. It is to benoted that in this example, the annular groove has a doubled structureof 27 a-8 and 27 b-8, which are spaced from each other in the radialdirection.

[0356] The flow rate of the high-pressure gas supplied to thehydrostatic bearing is in the order of about 20 L/min (in the conversioninto the atmospheric pressure). Assuming that the vacuum chamber C isexhausted by a dry pump having an exhaust velocity of 20,000 L/min via avacuum pipe having an inner diameter of 50 mm and a length of 2 m, thepressure in the vacuum chamber C will be about 160 Pa (about 1.2 Torr).At that time, with the applied size of the annular member 26-8, theannular groove and others of the differential pumping mechanism asdesignated in FIG. 39, the pressure within the charged particle beamirradiation space 30-8 can be controlled to 10-4 Pa (10-6 Torr).

[0357] It is to be appreciated that the differential pumping mechanismis not necessarily formed in a concentric circular geometry as in thismode but a rectangular or polygonal geometry may be applicable so far asthe differential pumping mechanism in such a shape can control thepressure within the charged particle beam irradiating space 30-8 to bemaintained at a predetermined level. Further, the differential pumpingmechanism is not necessarily provided along an entire circumference butmay be provided in some portions along the circumferential region.

[0358]FIG. 40 shows a second mode for carrying out the eighthembodiment. A vacuum chamber C defined by a housing 14-8 is connectedwith a dry vacuum pump 53-8 via vacuum pipes 74-8 and 75-8. An annulargroove 27-8 of a differential pumping mechanism 25-8 is connected withan ultra-high vacuum pump or a turbo molecular pump 51-8 via a vacuumpipe 70-8 connected to an exhaust port 28-8. Further, the interior of anelectron optical column 1-8 is connected with a turbo molecular pump52-8 via a vacuum pipe 71-8 connected to an exhaust port 18-8. Thoseturbo molecular pumps 51-8 and 52-8 are connected to the dry vacuum pump53-8 through vacuum pipes 72-8 and 73-8. (In FIG. 40, the single dryvacuum pump has been used to serve both as a roughing vacuum pump of theturbo molecular pump and as a pump for vacuum pumping of the chamber,but multiple dry vacuum pumps of separate systems may be employed forexhausting, depending on the flow rate of the high-pressure gas suppliedto the hydrostatic bearings of the XY stage, the volume and innersurface area of the vacuum chamber and the inner diameter and length ofthe vacuum pipes.) A high-purity inert gas (N₂ gas, Ar gas or the like)is supplied to a hydrostatic bearing of an XY stage 3-8 through aflexible pipes 21-8 and 22-8. Those gaseous molecules blown out of thehydrostatic bearing are diffused into the vacuum chamber and exhaustedby the dry vacuum pump 53-8 through exhaust ports 19-8, 20 a-8 and 20b-8. Further, those gaseous molecules having invaded into thedifferential pumping mechanism and/or the charged particle beamirradiation space are sucked from the annular groove 27-8 or the tipportion of the electron optical column 1-8 through the exhausting ports28-8 and 18-8 to be exhausted by the turbo molecular pumps 51-8 and52-8, and then those gaseous molecules, after having been exhausted bythe turbo molecular pumps, are further exhausted by the dry vacuum pump53-8.

[0359] In this way, the high-purity inert gas supplied to thehydrostatic bearing is collected into the dry vacuum pump and thenexhausted away.

[0360] On the other hand, the exhaust port of the dry vacuum pump 53-8is connected to a compressor 54-8 via a pipe 76-8, and the exhaust portof the compressor 54-8 is connected to flexible pipes 21-8 and 22-8 viapipes 77-8, 78-8 and 79-8 and regulators 61-8 and 62-8. Owing to thisconfiguration, the high-purity inert gas exhausted from the dry vacuumpump 53-8 is compressed again by the compressor 54-8 and then the gas,after being regulated to an appropriate pressure by the regulators 61-8and 62-8, is supplied again to the hydrostatic bearings of the XY stage.

[0361] In this regard, since the gas to be supplied to the hydrostaticbearings is required to be as highly purified as possible in order notto have any water contents or oil and fat contents included therein, asdescribed above, the turbo molecular pump, the dry pump and thecompressor are all required to have such structures that prevent anywater contents or oil and fat contents from entering the gas flow path.It is also considered effective that a cold trap, filter or the like(60-8) is provided in the course of the outlet side piping 77 of thecompressor so as to trap the impurities such as the water contents oroil and fat contents, if any, included in the circulating gas andprevent them from being supplied to the hydrostatic bearings.

[0362] This may allow the high purity inert gas to be circulated andreused, and thus allows the high-purity inert gas to be saved, while theinert gas would not remain discharged into a room where the presentapparatus is installed, thereby eliminating a fear that any accidentssuch as suffocation or the like would be caused by the inert gas.

[0363] It is to be noted that a circulation piping system is connectedwith the high-purity inert gas supply system 63-8, and the system 63-8serves both to fill up with the high-purity inert gas all of thecirculation systems including the vacuum chamber C, the vacuum pipes70-8 to 75-8, and the pipes in compression side 76-8 to 80-8, prior tothe starting of the gas circulation, and to supply a deficiency of gasif the flow rate of the circulation gas decreases by some reason.

[0364] Further, a single dry vacuum pump 53-8, if provided with afunction of compressing to the level equal or greater than theatmospheric pressure, may be employed so as to serve both as the dryvacuum pump 53-8 and the compressor 54-8.

[0365] Further, as to the ultra-high vacuum pump to be used forexhausting the electron optical column, other pumps including an ionpump and a getter pump may be used instead of the turbo molecular pump.It is to be note that in the case where those reservoir type pumps areused, the circulation systems are prohibited to build in those areas.Further, it is also apparent that instead of the dry vacuum pump, a drypump of other type, for example, a dry pump of diaphragm type may beused.

[0366] The electron beam apparatus to be installed in the electronoptical column 1-8 may employ any optical systems and detectors asdesired. For example, either of the image projection type shown in FIG.1 and the like or the scanning type shown in FIG. 41 and the like may beemployable.

[0367] According to the eighth embodiment of the present invention, thefollowing effects may be brought about.

[0368] (A) A processing by the charged particle beam can be stablyapplied to a sample on the stage by the use of the stage having astructure similar to that of a stage of hydrostatic bearing type whichis typically used in the atmospheric pressure (a stage supported by thehydrostatic bearing having no differential pumping mechanism).

[0369] (B) Affection on the vacuum level in the charged particle beamirradiation region can be minimized, and thereby the processing by thecharged particle beam to the sample can be stabilized.

[0370] (C) Such an inspection apparatus can be provided in low cost thataccomplishes positioning performance of the stage with high precisionand provides a stable vacuum level in the irradiation region of thecharged particle beam.

[0371] (D) Such an exposure apparatus can be provided in low cost thataccomplishes positioning performance of the stage with high precisionand provides a stable vacuum level in the irradiation region of thecharged particle beam.

[0372] (E) A micro semiconductor circuit can be formed by manufacturingthe semiconductor using an apparatus which accomplishes positioningperformance of the stage with high precision and provides a stablevacuum level in the irradiation region of the charged particle beam.

(Ninth Embodiment)

[0373] The defect inspection apparatus of FIG. 1 may be replaced with anelectron beam apparatus of scanning type. A configuration and operationof a ninth embodiment of the present invention relating to such ascanning type electron beam apparatus will now be described inconjunction with FIG. 41. In FIG. 41, an electron gun 1-9 comprises aWehnelt 31-9 and a cathode 32-9 and emits a primary electron beam havinga crossover of approximately 10 microns in diameter. The primaryelectron beam emitted in this way passes through deflectors 33-9 and34-9 for the axial alignment and then a condenser lens 2-9, where thebeam is converged thereby, and then after having passed through adeflector 12-9 and a Wien filter 8-9, the primary electron beam iscontracted by an objective lens 9-9 to form a probe of not greater than100 nm. Then, the contracted primary beam is formed into an image on oneof a plurality of, for example, rectangular circuit patterns formed on asurface of a sample 10-9 loaded on a stage S-9. The sample 10-9 isapplied with a scanning by the primary electron beam using thedeflectors 12-9 and 40-9.

[0374] A secondary electron beam, which has been emitted from thesurface of the sample 10-9 as a result of the scanning with the primaryelectron beam, is attracted and accelerated by an electric field of theobjective lens 9-9 and deflected by the Wien filter 8-9 so as to departfrom an optical axis L and thus to be separated from the primaryelectron beam. In this way, the secondary electron beam is detected by asecondary electron beam detecting section 41-9. The secondary electrondetecting section 41-9 outputs an electric signal representing anintensity of the secondary electron beam entered therein. The electricsignal output from this secondary electron detecting section 41-9 isamplified by a corresponding amplifier (not shown) and then entered intoan image processing section 42-9.

[0375] As shown in FIG. 41, the electron gun 1-9, the deflectors 33-9and 34-9 for the axial alignment, the condenser lens 2-9, the deflector12-9, the Wien filter 8-9, the objective lens 9-9 and the secondaryelectron detecting section 41-9 are all accommodated in an electronoptical column 43-9 having a diameter corresponding to a predeterminedextent on the sample 10-9 thus to make up a single unit of electron beamscanning and detecting system 44-9, and this single unit of electronbeam scanning and detecting system 44-9 is used to scan a circuitpattern on the sample 10-9. In specific, there is a plurality of diesformed on a surface of the sample 10-9. Another electron beam scanningand detecting system (not shown) having a similar configuration to thatof the electron beam scanning and detecting system 44-9 may be arrangedin parallel with the electron optical column 43-9 so as to scan the samelocation on a different die on the sample 10-9.

[0376] As having been described already in conjunction with the electronbeam scanning and detecting system 44-9, the electric signal output fromeach of the secondary electron detecting systems in the electron beamscanning and detecting system is entered into the image processingsection 42-9. Then, the image processing section 42-9 converts theelectric signal having been entered from the each of the detectingsystems into a binary information, and further converts this binaryinformation into an image data with reference to the electron beamscanning signal. To accomplish this, a signal waveform having applied tothe electrostatic deflector 12-9 is supplied to the image processingsection 42-9. The image data obtained for each of the dies formed on thesurface of the sample 10-9 is compared with a reference die patternwhile being accumulated in an appropriate storage means. This allows anydefects to be detected for every one of the plurality of die patternsformed on the surface of the sample 10-9.

[0377] It is to be noted that in the mode for carrying out theembodiment shown in FIG. 41, a variety of circuit patterns may be usedas a reference circuit pattern to be used by the image processingsection 42-9 for making a comparison with a specific image datarepresenting a certain die pattern on the sample 10-9, and for example,such image data obtained from the CAD data for the die pattern, to whichthe scanning has been applied so as to generate said specific imagedata, may be used.

[0378] The Wien filter 8-9 comprises an electrostatic deflector 39-9 andan electromagnetic deflector 40-9 arranged so as to circumscribe saidelectrostatic deflector 39-9. As for this electromagnetic deflector40-9, preferably a permanent magnet made of platinum alloy may be usedinstead of an electromagnetic coil. This is because applying a currentin a vacuum environment is not adequate. Further, the deflector 12-9 maybe used also as an axial aligner for aligning the direction of theprimary electron beam with the axis of the objective lens 9-9.

[0379] To fabricate the condenser lens 2-9 and the objective lens 9-9 inthe electron beam scanning and detecting system 44-9, at first a ceramicblock is processed in high precision to be formed into a shape ofsectional geometry shown in FIG. 41 and then a metal coating isselectively applied to a surface of the processed ceramic so as to forman upper electrode 35-9, a central electrode 36-9 and a lower electrode37-9, respectively. To the upper electrode 35-9 is applied a voltageproximal to a ground voltage and to the central electrode 36-9 isapplied a positive or negative voltage having a high absolute valuethrough a current introduction terminal 38-9 made of metal, therebyproducing a lens effect.

[0380] In this way, since the condenser lens 2-9 and the objective lens9-9 are fabricated by way of machining of the ceramic, it is possible toprocess those lenses with high level of precision and to reduce outerdiameters thereof. Accordingly, if the outer diameters of the condenserlens 2-9 and the objective lens 9-9 are reduced to, for example, notgreater than 20 mm, then six electron beam scanning and detectingsystems can be arranged in the case of the inspection of the waferhaving a diameter of 200 mm with a range defined by a diameter of 140 mmto be inspected, thus achieving the throughput increased by six times.

[0381] A characteristic part in the embodiment of the electron beamapparatus according to the present invention will be described below.The objective lens 9-9 is constituted of an electrostatic lens, and toeither one of the electrodes of the electrostatic lens is applied a highpositive voltage. On the other hand, to the sample wafer 10-9 is applieda high negative voltage by a power supply 20-9. This produces adecelerating electric field between the objective lens 9-9 and thesample wafer 10-9.

[0382] If the wafer 10-9 is a wafer having a via and the primaryelectron beam enters into the via, then a large amount of secondaryelectrons would be emitted because the via is made of metal with highatomic number. Further, in the vicinity of the via, much larger electricfield would have been generated locally due to the decelerating electricfield. Because of those facts, a wafer with the via is in a conditionwhere an electric discharge is likely to occur therearound.

[0383] However, given all of those conditions, the electric dischargewould not necessarily occur instantly. At first, a corona dischargewould occur in which a residual gas in a space of intense electric fieldemits light locally, and then the corona discharge is to be shifted toan arc discharge through a transient state of a spark discharge. In thisspecification, a period from the event of this corona discharge to thebeginning of the spark discharge will be referred to as a “precursoryphenomenon of the electric discharge”.

[0384] It has been found that in the period corresponding to thisprecursory phenomenon of the electric discharge, if the beam current isdecreased so as to limit the generation of the primary electron beam toa quantity not greater than a certain level or the voltage of thedecelerating electric field between the objective lens 9-9 and thesample wafer 10-9 is decreased, or otherwise both of those arrangementsare performed, then it can inhibit the precursory phenomenon fromproceeding to the arc discharge and thus can prevent any damage to thewafer.

[0385] Beside, since critical levels for the decelerating electric fieldvoltage or the primary electron beam dose not to trigger the electricdischarge are different between an easily discharged wafer and a hardlydischarged wafer, therefore those values should not be fixed at lowlevels but it is preferable to obtain limit values for prohibiting theelectric discharge for each type of the wafer.

[0386] In an electron beam apparatus according to the present inventionas shown in FIG. 41, a PMT 19-9 and an ampere meter for a sample 21-9are provided as a detector for detecting the electric discharge or theprecursory phenomenon of the electric discharge between the sample wafer10-9 and the objective lens 9-9 and generating a signal. The PMT 19-9can detect the light emission by the corona discharge or the arcdischarge and the ampere meter for the sample 21-9 can detect anirregular current at the time of the corona discharge or the arcdischarge.

[0387] If the PMT 19-9 detects the light emission by the coronadischarge or the ampere meter for the sample 21-9 detects the irregularcurrent in the period of the precursory phenomenon of the electricdischarge, such information may be entered to a CPU 22-9. A voltagevalue of the decelerating electric field and a beam current value(corresponding to the primary electron beam dose) of the electron gun1-9 measured at that time may be used as basic data for determining acondition not to trigger the electric discharge. The CPU 22-9, inresponse to the entry indicating the presence of the light emission orthe irregular current or both of them, performs such a control that, forexample, it reduces the voltage of the decelerating electric field 20-9or it sends a feedback signal to the electron gun 1-9 to decrease thebeam current thus to control the primary electron beam dose to a valuenot greater than a specified level. The CPU 22-9 may perform both ofthose two controls.

[0388] Preferably both of the PMT 19-9 and the ampere meter for thesample 21-9 should be employed, but either one of them may be omitted.

[0389]FIG. 42 shows an arrangement of devices on a single wafer. Aplurality of rectangular chips 51-9 is obtained from a single circularwafer 50-9, and there are defective chips existing in a circumferentialregion thereof, which are insufficient in size for a single chip. Anormal lithography is also applied to those regions having defectivechips and various processes are also applied to those regions similarlyto the region having a complete chip 51-9. On the other hand, sincethose defective chips would not be used as finished products and anydamages to those regions would not be a problem. In this viewpoint, ifsaid regions having the defective chips are used so as not only todetect the precursory phenomenon of the electric discharge but also todetect further the phenomenon of the electric discharge withoutflinching from the possible break, then it can help determine moreprecisely a condition for preventing the electric discharge. In thiscase, the PMT 19-9 may detect the light emission by the arc discharge,and the ampere meter for the sample 21-9 may detect the irregularcurrent at the time of the arc discharge and then send a signal to theCPU 22-9. Further, the CPU 22-9 can designate accurately the limitvalues representing the voltage value of the decelerating electric filedand the beam current value (corresponding to the primary electron beamdose) not to trigger the electric discharge.

[0390] According to the electron beam apparatus of the ninth embodiment,the condition not to trigger the electric discharge can be determinedindividually depending on the wafer which is easily discharged or hardlydischarged.

[0391] Further, if the regions having defective chips (incomplete chips)are used to perform a further level of detection such as the detectionof the phenomenon of the electric discharge, a critical condition not totrigger the electric discharge can be known accurately. Alternatively,in the case where the regions having normal chips (complete chips) areused, if the detection is limited to a level of the detection of theprecursory phenomenon of the electric discharge, the condition not totrigger the discharge can be known to an effective level still with nodamage to the normal chips. In either case, since the normal chips arenever be broken, an evaluation procedure of a wafer can be conductedwith high throughput, that is, with a favorable condition for thedetection efficiency of the secondary electrons. Use of the multi-beammay further improve the throughput.

(Tenth Embodiment)

[0392] Preferred embodiments of a scanning type electron beam apparatusaccording to a tenth embodiment of the present invention will now bedescribed with reference to the attached drawings. FIG. 43 showsschematically an electron beam apparatus according to the tenthembodiment of the present invention. As shown in FIG. 43, the electronbeam apparatus comprises a plurality of electron optical columns 60-10(eight lens columns shown in this embodiment), each being composed ofthe same components, arranged in parallel above a sample 43-10. One ofthose electron optical columns 6-10 has an electron gun 20-10, axialaligning electrodes 24-10 and 25-10 for the axial alignment of a primaryelectron beam, a condenser lens 61-10, an electrostatic deflector 27-10for scanning with the primary electron beam, an E x B separator 62-1consisting of an electromagnetic deflector 29-10 and an electrostaticdeflector 30-10, an objective lens 41-10, an axially symmetric electrode42-10 for measuring a voltage contrast, and a detector 28-10 serving asa detecting means on which a secondary electron beam separated from theprimary electron beam forms an image and which detects a detectionsignal of the secondary electron beam.

[0393] The electron gun 20-10 comprises a Schottky shield 21-10, ashottokey cathode 22-10, and an anode 23-10, and it works to emit theprimary electron beam. The primary electron beam emitted from theelectron gun 20-10 is controlled to be in axial alignment with respectto a condenser lens 61-10 by the axial aligning electrodes 24-10, 25-10,and then is converged by the condenser lens 61-10. The primary electronbeam converged by the condenser lens 61-10 forms an image on a sample43-10 with an aid of the objective lens 41-10. At the same time, theelectrostatic deflector 27-10 and the electromagnetic deflector 29-10 ofthe E x B separator 62-10 deflect the beam so as to scan a surface ofthe sample 43-10. Since an angle of deflection by the electromagneticdeflector 29-10 has been set to approximately doubled angle ofdeflection by the electrostatic deflector 27-10, there would begenerated no chromatic aberration by deflection.

[0394] The secondary electron beam emitted from the scanned point on thesample 43-10 is attracted and accelerated by a high positive voltageapplied to a central electrode of the objective lens 41-10, separatedfrom the primary optical system by the E x B separator 62-10, introducedinto the secondary optical system, and then formed into an image on thedetector 28-10.

[0395] The detector 28-10 outputs the image of the secondary electronbeam formed thereon to a low-pass filter (LPF) 2-10 in a form of anelectric signal representing its intensity (a detection signal of thesecondary electron beam). To explain in more specific, the electricsignal output from the detector 28-10 is firstly amplified by theamplifier 1-10 and then output to the low-pass filter (LPF) 2-10. Thelow-pass filter 2-10 is such a device that allows only the electricsignal having a frequency of pass band to pass though it, and theelectric signal which has passed through the low-pas filter 2-10 isconverted by an A/D converter 3-10 from the analog signal to a digitalsignal, which in turn is sent to an image forming unit 4-10. Further,the image forming unit 4-10 is further supplied with a scanning signal,which has given to the electrostatic deflector 27-10 and theelectromagnetic deflector 29-10 from a deflector control power supply5-10 for deflecting the primary electron beam. The image forming unit4-10 can synthesize image data from the scanning signal and the electricsignal to constitute or display the image representing the scannedsurface of the sample 43-10. Comparing this image data with a referenceimage data having no defect allows a defect on the sample 43-10 to bedetected.

[0396] The low-pass filter 2-10 will now be described in detail, whichis a characteristic part of the present invention. The low-pass filter2-10 is such a device that allows only the electric signal having afrequency of pass band to pass though it, as described before. FIG.44(A) shows a pattern on a sample. This pattern includes portions 31-10that have been recessed by 0.5 μm by etching and portions 32-10 that arenot etched and are 0.5 μm higher than the etched portions 31-10, whichtwo kinds of portions have been alternately formed therein.

[0397] FIGS. 44(B) and (C) show waveforms of aforementioned electricsignal (detection signal of the secondary electron beam) received by theimage forming unit 4-10, wherein FIG. 44(B) shows a signal waveform in acase where the electric signal outputted from the detector 28-10 isreceived by the image forming unit 4-10 without passing through thelow-pass filter 2-10, while FIG. 44(C) shows another signal waveform ina case where the electric signal outputted from the detector 28-10 isreceived by the image forming unit 4-10 after having passed through thelow-pass filter 2-10. It is to be noted that herein the pixel frequencyis 10 MHz and the amplifier 1-10 allows the frequency up to 100 MHz topass. Further, the low-pass filter 2-10 has frequency characteristicswith a frequency of 20 MHz for 3 db signals dropping at the rate of 12db/octave.

[0398] It is observed that the signal waveform shown in FIG. 44(B) hasthe intensity of the electric signal increased at the edge portions ofthe pattern as indicated by reference numeral 33-10. Besides, it is alsoobserved that the intensity of the electric signal is reduced at the endportions of the grooves of the pattern as indicated by reference numeral34-10. On the other hand, it is found that, as indicated by referencenumeral 35-10, the signal waveform shown in FIG. 44(C) has the intensityof the electric signal observed at the edge portions of the patternbeing smaller than that as shown in FIG. 44(B). Further, as indicated byreference numeral 36-10, the intensity of the electric signal observedat the end portions of the grooves of the pattern appears to be shallowin depth as compared to that shown in FIG. 44(B).

[0399] In this way, allowing the electric signal outputted from thedetector 28-10 to pass through the low-pass filter 2-10 and then to bereceived by the image forming unit 4-10 can reduce the intensity of theelectric signal at the edge portions of the pattern where the secondaryelectron emission rate is extremely high. Thus, this can prohibit thatthe electric signal at the portions having the extremely high secondaryelectron emission rate would mask such a signal as occurred from adefect, and can improve the defect inspection speed.

[0400] On the other hand, for an aluminum pattern, the intensity of theelectric signal at the edge portions would not be increased to thathigh, so that, in this case, a more accurate pattern image can beobtained by allowing the image forming unit 4-10 to receive highfrequency signal. Therefore, if said low-pass filter 2-10 has beendesigned to have the variable cut-off frequency, the image data can besuccessfully detected for any patterns and thus the detection rate canbe further improved.

[0401] Further, although in the above embodiment, having been arrangedbetween the amplifier 1-10 and the A/D converter 3-10, the low-passfilter 2-10 may be located between the detector 28-10 and the amplifier1-10 or between the A/D converter 3-10 and the image forming unit 4-10.

[0402] On the other hand, a shot noise “i_(n) ²” can be represented byan equation, i_(n) ²=2eIB, which means that the noise could be madesmaller as a signal bandwidth “B” is reduced, which provides the signalwith large S/N ratio. Where, “e” denotes a charge of an electron and “I”denotes a current.

[0403] Further, as shown in FIG. 43, the condenser lens 61-10 is such alens that is made by processing an insulating material or ceramic toform a plurality of electrodes in one unit and then selectively applyinga metal coating onto a surface thereof. The plurality of electrodes inthe condenser lens 61-10 is composed of an upper electrode 44-10, acentral electrode 45-10, and a lower electrode 46-10, and to thecondenser lens 61-10 is applied a voltage via a lead mounting bracket47-10. Besides, similarly to the condenser lens 61-10, the objectivelens 41-10 is also a lens that is made by processing an insulatingmaterial or ceramic to form a plurality of electrodes in one unit andthen selectively applying a metal coating onto a surface thereof. Sincethe condenser lens 61-10 and the objective lens 41-10, which have beenprocessed in such a manner, can be made as the lens of smaller outerdiameters and thereby allows the outer diameter of the electron opticalcolumn 6-10 to be made smaller, therefore a large number of electronoptical columns 6-10 can be arranged in parallel above a single sample43-10.

[0404] According to the tenth embodiment, since there is provided anelectron beam apparatus comprising a plurality of electron opticalcolumns arranged in parallel, each being designed so as to form theprimary electron beam into an image on the sample and to form thesecondary electron beam emitted from the sample into an image on thedetecting means, wherein said apparatus further comprises a low-passfilter, and said detecting means outputs the detection signal of thesecondary electron beam to said low-pass filter, therefore the apparatuscan reduce a signal intensity of the detection signal having a highlevel of secondary electron emission rate and also exhibiting a waveformof pulse shape with narrow width, thereby improving the defect detectionrate.

(Eleventh Embodiment)

[0405] First of all, referring to FIG. 45, an evaluation apparatus forevaluating a condition of a wafer for a semiconductor device afterhaving been processed according to the present invention will bedescribed.

[0406] In FIG. 45, reference numeral 1-11 is an electron gun foremitting an electron beam, 2-11 is a cathode, 3-11 is an anode, 4-11,5-11 and 27-11 are deflectors, 26-11 is a condenser lens, and 29-11 and30-11 are deflectors which make up an E x B separator. The referencenumeral 31-11 is an objective lens, 33-11 is a wafer prepared as aninspection sample, and 28-11 is an electron beam detector. Further, thereference numeral 12-11 is an image forming unit, and 13-11 is ascanning control unit, which supplies the deflectors 27-11 and 29-11with a scanning signal used for scanning operation of the electron beam.

[0407] In the evaluation apparatus of FIG. 45, the electron beam emittedfrom the electron gun 1-11 forms an image on a surface of the wafer33-11 with an aid of the condenser lens 26-11 and an objective lens31-11, while scanning the surface of the wafer 33-11 with an aid of thedeflectors 27-11 and 29-11. Under the condition where a stage (notshown) holding the wafer 33-1 has been held stationary, the scanningcontrol circuit 13-11 controls the deflectors 27-11 and the 29-11 sothat either one of them may control the electron beam to scan in theX-axis direction and the other may control the electron beam to scan inthe Y-axis direction. This allows a raster scanning to be applied to thesurface of the wafer 33-11 while the wafer 33-11 being fixed, and theelectron beam spot may be formed on every point within a predeterminedarea on the surface of the wafer 33-11.

[0408] In this stage, if one time of the raster scanning is not enoughto cover entire region to be inspected on the wafer, which has beendetermined in advance, the stage having the wafer 33-11 loaded thereonshould be moved step by step in the X-axis and/or the Y-axis directions,so that the areas adjacent to those areas which have been previouslyscanned can be similarly scanned.

[0409] A secondary electron beam emitted by the electron beam forming animage on the wafer 33-11 is deflected by the E x B separator or thedeflectors 29-1, 30-11, converted into an electric signal by thesecondary electron beam detector 28-11, and supplied as a detectionsignal to the image forming unit 12-11.

[0410] The condenser lens 26-11 comprises an upper electrode 34-11, acentral electrode 35-11 and a lower electrode 36-11 formed therein,which have been formed in such a way that a single cylindrical body ofceramic is skived so as to be axially symmetric in sectional geometryand to have three arms whose surfaces are then selectively applied witha metal coating to be formed into respective electrodes. The centralelectrode 35-11 is supplied with an electric power through a currentintroducing terminal 37-11, and the upper electrode 34-11 and the lowerelectrode 36-11 are supplied with the electric power respectivelythrough those metal-coated sections in the outer peripheral portion ofthe condenser lens 26-11 serving as power supplying terminals. With thecondenser lens 26-11 which has been constituted by an axially symmetriclens formed as one body in the manner as described above, the outsidedimension thereof has been successfully reduced with a diameter reducedto about 40 mm.

[0411] The objective lens 31-11 has been made so as to haveapproximately similar configuration and dimension to the condenser lens26-11.

[0412] The image forming unit 12-11 is also supplied with the scanningsignal from the scanning control unit 13-11, in which the output signalfrom the detector is coordinated so as to correspond to the scanningsignal and then stored in an image data storage (not shown) as a signalrepresenting a pixel locations. With this signal, the image of thesurface of the wafer 33-11 can be formed by the image forming unit12-11.

[0413] The image representing the wafer surface which has been formed insuch a manner as described above is then compared as per pixel by amismatch/match detecting unit (not shown) with a reference image patternor an image pattern with no defect stored in advance, and if anymismatching pixel is found out, then it may be determined that the waferhas a defect. If the evaluation result of a wafer is different from theevaluation results of large majority of wafers, it may be determinedthat said wafer has a defect. Further, the image representing the wafersurface may be displayed on the monitor screen, and in that case anexperienced operator or the like may monitor the image to inspect thewafer surface for a defect.

[0414] Still further, upon measuring a line width of a wiring pattern oran electrode pattern formed on the wafer, a pattern area to be evaluatedis moved to a location on or near to an optical axis and said area isline-scanned to take out an electric signal to be used for evaluatingthe line width, while applying a calibration to the signal if necessary,thereby detecting the line width.

[0415] With an evaluation apparatus having such a configuration asdescribed above, the present invention has suggested a method in orderto inspect the wafer surface which has been processed by a processingapparatus, in which the evaluation apparatus is arranged in theproximity to the processing apparatus and further a controller (notshown) controls an overall operation of the evaluation apparatus toinspect only a region consisting of a predetermined one area or aplurality of predetermined areas on the wafer surface so that aninspection time may be made approximately equal to a processing time perwafer by said processing apparatus. In this control, at first the waferis secured to the evaluation apparatus, and then minimal requiredevaluation parameter of a wafer and a processing time required for eachwafer are input to the controller of the evaluation apparatus. Theevaluation parameter includes, for example, a fluctuation of a minimumline width in the case of the processing apparatus being a lithographyapparatus and a defect inspection in the case of the processingapparatus being an etching apparatus. Subsequently, the controllerdetermines an evaluation area on the wafer based on the enteredevaluation parameter and the entered processing time required so thatthe time required per wafer for evaluating a processed condition of thewafer may be made within or approximately equal to the processing timerequired per wafer.

[0416] Since the inspection is only applied to the predetermined areaand inevitably the range of movement of the wafer 33-11 within theevaluation apparatus should be made smaller, therefore a floor area ofthe evaluation apparatus can be reduced in comparison to the case wherethe inspection is applied to the entire area on the wafer. Further,since the evaluation time has been made approximately equal to theprocessing time, therefore if any defect is found out, it will be moreeasier to find out any irregular operation in the processing apparatuscorresponding to the defective condition.

[0417] A second mode for implementing an evaluation apparatus accordingto the eleventh embodiment of the present invention will now bedescribed. In this second mode, the evaluation apparatus of the firstmode as shown in FIG. 45 has been used as a single unit of electronoptical column, and the entire evaluation apparatus comprises eightunits of electron optical columns arranged in an array of 4×2 (4electron optical columns in the X-axis direction and 2 electron opticalcolumns in the Y-axis direction) as shown in FIG. 46, thus constitutingthe evaluation apparatus.

[0418] As having been discussed in conjunction with the first mode, theouter diameter of the condenser lens 26-11 and the objective lens 31-11could have been reduced to about 40 mm, and thereby the outer diameterof the electron optical column could have been reduced to about 42 mm.Accordingly, with the electron optical column having the diameter of 42mm, four electron optical columns may be arranged in a tight contact toeach other along the X-axis on an 8-inch (about 203 mm) wafer with atotal length of 189 mm (147 mm+42 mm) as shown in FIG. 46. Beside, asshown in FIG. 46, if the electron optical columns are also arranged in atight contact to each other along the Y-axis so as to form the array of4×2, totally 8 of the electron beams can be used for raster-scanning onthe wafer surface all at once.

[0419] It is to be appreciated that the physical relationship among aplurality of electron optical columns and the number of the electronoptical columns are not limited to those shown in FIG. 46, but ofcourse, M×N array may be employed (M and N are integers selectedarbitrarily). In that case, they are required to be arranged such thatthe optical axes of those electron beams are equally spaced along theX-axis.

[0420] Even in the second mode employing a plurality of electron opticalcolumns, similarly to the fist mode, the evaluation apparatus isarranged in the proximity to the processing apparatus and further acontroller (not shown) controls the operation of the evaluation so thatthe inspection time may be made approximately equal to the processingtime required for each wafer by said processing apparatus. In this case,since the inspection time has been made shorter by employing a pluralityof electron optical columns, therefore the entire area on the wafer maybe determined to be the region subject to inspection if the processingtime allows to do so. Alternatively, some of the wafers may be appliedwith a full-face inspection and the other may be applied with noinspection. The point is that the inspection condition should be setsuch that the processing time per a wafer or per a lot may be madeapproximately equal to the inspection time therefor.

[0421] With the second mode also, since the range of movement of thestage on which the wafer is loaded should be made smaller, therefore afloor area of the evaluation apparatus can be reduced. Further, sincethe throughput of the evaluation apparatus is made approximately equalto the throughput of the processing apparatus, if a defect is found out,it will be much easier to find out an abnormal operation in theprocessing apparatus.

[0422] Besides, upon evaluating a processed condition in a processingapparatus with an especially shorter processing time, a samplinginspection on the basis of one for every two wafers or one for everythree wafers may be applied so as to make the evaluation time requiredper a lot approximately equal to the processing time required a per lot.

[0423] According to the evaluation apparatus of eleventh embodimentwhich has been configured as described above, the miniaturization of anevaluation apparatus for a wafer of a semiconductor device can beaccomplished, while the throughput of the evaluation apparatus can bematched with the throughput of the processing apparatus. Thereby, at thepoint of detection of a wafer having a defect, a real time checking ofthe operation can be applied to the processing apparatus and it mayreduce a fear that the processing apparatus would continue tomanufacture defective wafers undesirably.

(Twelfth Embodiment)

[0424] A twelfth embodiment of the present invention will now bedescribed with reference to the drawings. FIG. 47 is a graph indicatingrelationships of MTF, (MTF)², I_(p), and (MTF)⁴I_(p) as a function ofD/d, while FIG. 48 is a block diagram illustrating a generalconfiguration of an optical system of an electron beam apparatus of thescanning type according to the twelfth embodiment. As shown in FIG. 48,the electron gun 20-12 comprises a TFE cathode 22-12 to be locatedwithin a Wehnelt 21-12 and an anode 23-12 to be located outside to theWehnelt 21-12, in which an electron beam is emitted from the TFE cathode22-12 toward the anode 23-12 and the electron beam, after passingthrough the anode 23-12, is axially aligned by axially aligningdeflectors 24-12 and 25-12 so as to pass through a condenser lenses34-12, 35-12 and 36-12 at the central locations thereof.

[0425] The electron beam converged by the condenser lenses 34-12, 35-12and 36-12 forms a crossover on a deflection center of an E x B separator30-12 and the beam is further focused on a sample 33-12 by an objectivelens 31-12. The electron beam scans a surface of the sample 33-12 withan aid of an electrostatic deflector 27-12 to be located beneath thecondenser lens and an electromagnetic deflector 29-12 to be located overthe E x B separator 30-12. A secondary electron beam emitted from apoint of scanning on the sample 33-12 is accelerated by an electricfield generated by the objective lens 31-12, where the beam is furtherconverged to be narrower and passes through the objective lens 31-12.The converged secondary electron beam is deflected by the E x Bseparator 30-12 disposed right above the objective lens 31-12, into thedirection indicated by the dotted line so as to be separated from theprimary electron beam, and then the secondary electron beam is detectedby the secondary electron detector 28-12 to be converted into an imagesignal.

[0426] In the electron beam apparatus of FIG. 48, a defect inspection ofa sample may be performed in such a way that the electron beam scans thesurface of the sample 33-12 with a width of 200 μm in the x-direction(vertical direction in page space of FIG. 48) while the stage 38-12being successively moved in the y-direction. When the defect inspectionwith the width of 200 μm has been finished up to an end along they-direction on the sample (a limited region), the stage 38-12 is movedin the x-direction by only 201 μm to inspect an adjacent stripe (anadjacent region). Because the stage has been moved by 1 μm more than thewidth of the limited region, there would be a region of 1 μm remainednot-inspected, but this can eliminate any overlaps of the scanningregions and prevent a damage to the sample. Further, the damage to thesample can be minimized by no electron beam radiated onto the sampleduring no date of the electron beam scanning being taken in.

[0427] Although in the above case, there is a not-inspected region of 1μm remained due to avoiding the scanning regions overlapping one on theother, the area for non

What claimed is:
 1. A substrate inspection apparatus, comprising: a. abeam source for emitting an electron beam having a specified width; b. aprimary electron optical system for introducing said electron beam to asurface of a substrate subject to an inspection; c. a secondary electronoptical system for guiding secondary electrons emitted from saidsubstrate to a detecting system; d. an image processing system forforming a secondary electron image based on a detection signal of asecondary electron beam obtained by said detecting system; e. a stagefor holding said substrate in such a manner that said substrate may bemoved successively with at least one degree of freedom; f. an inspectionchamber for said substrate; g. a substrate conveying mechanism capableof carrying said substrate into said inspection chamber and taking outit therefrom; h. an image processing analyzer capable of detecting adefective location on the substrate loaded into said inspection chamberbased on the secondary electron image formed by said image processingsystem; i. a vibration isolating mechanism for said inspection chamber;j. a vacuum system capable of controlling a vacuum atmosphere to bemaintained in said inspection chamber; and k. a control system forindicating and/or storing said detective location on said substratedetected by said image processing analyzer.
 2. The substrate inspectionapparatus in accordance with claim 1, further comprising: amini-environment device for inhibiting dust from adhering to thesubstrate by applying a purge gas flow against said substrate prior tothe inspection; and at least two loading chambers which are disposedbetween said mini-environment device and said inspection chamber andcontrollable to the vacuum atmosphere independently from each other,wherein said substrate conveying mechanism includes a loader having oneconveying unit capable of conveying said substrate between saidmini-environment device and one of said loading chambers and anotherconveying unit capable of conveying said substrate between one of saidloading chambers and said stage, and said vibration isolating mechanismincludes a vibration isolating unit interposed between said inspectionchamber and said loading chamber.
 3. The substrate inspection apparatusin accordance with claim 1, further comprising a pre-charge unit forirradiating an electron beam onto said substrate disposed in saidinspection chamber to reduce non-uniformity level in an electro staticcharge on said substrate and a potential applying mechanism for applyinga potential to said substrate.
 4. The substrate inspection apparatus inaccordance with claim 1, further comprising an alignment control unitfor observing a surface of said substrate and controlling an alignmentthereof in order to position said substrate in place with respect tosaid primary electron optical system, and a laser-interferometer formeasuring a coordinate of said substrate on said stage, wherein saidalignment control unit uses a pattern existing on said substrate todetermine the coordinate of a subject to be inspected.
 5. The substrateinspection apparatus in accordance with claim 1, in which said detectingsystem comprises an MCP for multipling said secondary electron beam, afluorescent screen for converting said amplified secondary electron beaminto an optical signal and a CCD camera or a line sensor for taking outsaid optical signal as an image data, wherein a voltage applied to saidMCP is controlled in association with a change in the amplificationfactor of the MCP in order to determine an optimal amount of exposurefor the image containing said defect.
 6. The substrate inspectionapparatus in accordance with claim 1, in which said inspection systemcomprises an MCP for amplifying said secondary electron beam, afluorescent screen for converting said amplified secondary electron beaminto an optical signal and a CCD camera or a line sensor for taking outsaid optical signal as an image data, wherein an emission current ofsaid electron beam is controlled in association with a change in theamplification factor of the MCP in order to determine an optimal amountof exposure for the image containing said defect.
 7. The substrateinspection apparatus in accordance with claim 5, in which said voltageapplied to said MCP is determined by referring to a current MCP appliedvoltage-MCP gain curve.
 8. The substrate inspection apparatus inaccordance with any one of claims 5 to 7, in which said MCP appliedvoltage or said emission current of the beam is controlled inassociation with a multiplying factor of projection of the electron beamor a change in a line rate of said line sensor.
 9. The substrateinspection apparatus in accordance with claim 1, in which said detectingsystem is incorporated with a feed-through unit, said feed-through unitcomprising: a feed-through section made of an electrical insulatingmaterial; at least one electricity introduction pin fixedly attached tosaid feed-through section; and a connecting wiring for connecting saidat least one electricity introduction pin with a functional element,wherein said functional element includes a sensor, and both a pressureand a kind of gas in an inside of said feed-through section aredifferent from those of an outside thereof, respectively.
 10. Thesubstrate inspection apparatus in accordance with claim 9, in which saidfunctional element is arranged on an inner surface of said feed-throughsection and said functional element includes a CCD or a TDI sensor. 11.The substrate inspection apparatus in accordance with claim 9 or 10, inwhich a wiring is formed in a net-like configuration on a surface ofsaid feed-through section.
 12. The substrate inspection apparatus inaccordance with any one of claims 9 to 11, further comprising a metalflange.
 13. The substrate inspection apparatus in accordance with anyone of claims 9 to 12, in which said electricity introduction pintransmits a signal with frequency of not less than 10 MHz.
 14. Thesubstrate inspection apparatus in accordance with claim 1, in which saidbeam source is an electron beam source comprising a Wehnelt electrode,wherein said apparatus further comprises a control section forcontrolling a voltage applied to said Wehnelt electrode with time sothat an emission current flowing to said electron beam source can bemaintained at a constant level.
 15. The substrate inspection apparatusin accordance with claim 14, in which said electron beam sourcecomprises an electron gun having a cathode made of LaB₆.
 16. Thesubstrate inspection apparatus in accordance with claim 15, in which aflat <100>mono-crystalline orientation having a diameter of not lessthan 100 microns is arranged in a tip portion of said cathode.
 17. Thesubstrate inspection apparatus in accordance with claim 1, in which saidstage is provided with a non-contact supporting mechanism by means of ahydrostatic bearing and a vacuum sealing mechanism by means of adifferential pumping, and a divider is arranged between a location onsaid substrate subject to the electron beam irradiation and ahydrostatic bearing supporting section of said stage so as to reduce aconductance, so that a pressure difference may be generated between theelectron beam irradiated region and said hydrostatic bearing supportingsection.
 18. The substrate inspection apparatus in accordance with claim17, in which said divider includes a differential pumping structurebuilt therein.
 19. The substrate inspection apparatus in accordance withclaim 17 or 18, in which said divider has a cold trap function.
 20. Thesubstrate inspection apparatus in accordance with any one of claims 17to 19, in which said divider is arranged at each of two locations, whichcorrespond to the vicinity of the charged particle beam irradiatinglocation and the vicinity of the hydrostatic bearing, respectively. 21.The substrate inspection apparatus in accordance with any one of claims17 to 20, in which the gas supplied to said hydrostatic bearing of saidstage is either of a dry nitrogen or a highly purified inert gas. 22.The substrate inspection apparatus in accordance with any one of claims17 to 21, in which at least a surface of a component of said stagefacing to the hydrostatic bearing has been provided with a surfacetreatment for reducing gas emanated therefrom.
 23. The substrateinspection apparatus in accordance with claim 17 in which said stage isaccommodated in a housing of said inspection chamber and supported by ahydrostatic bearing in a non-contact manner, wherein said housingcontaining said stage is evacuated to vacuum, and a differential pumpingmechanism is arranged in a surrounding of a section irradiating theelectron beam onto said substrate surface, for evacuating a region onsaid substrate subject to an electron beam irradiation.
 24. Thesubstrate inspection apparatus in accordance with claim 23, in which agas supplied to said hydrostatic bearing of said stage is either of adry nitrogen or a said highly purified inert gas, wherein said drynitrogen or said highly purified inert gas, after having been exhaustedfrom said housing containing said stage, is pressurized and suppliedagain to said hydrostatic bearing.
 25. The substrate inspectionapparatus in accordance with claim 1, further having, in addition to animage projecting function comprising the steps of irradiating theelectron beam having said specified width onto the substrate andprojecting the secondary electron image onto said detecting system bymeans of said secondary electron optical system, a scanning electronmicroscopy function comprising the steps of firstly forming an electronbeam to be narrower than said specified width, secondarily irradiatingsaid narrower electron beam onto and scanning thereby the substratesurface, and lastly detecting the secondary electron beam emitted fromsaid substrate.
 26. The substrate inspection apparatus in accordancewith claim 25, in which the function can be switched appropriatelybetween said image projecting function and said scanning electronmicroscopy function to each other in response to a condition of thesubstrate during a single substrate being inspected.
 27. The substrateinspection apparatus in accordance with claim 26, in which, on the samesubstrate, a pattern of a hardly charged sample area is inspected byusing said image projecting function and a pattern of an easily chargedsample area is inspected by using said scanning electron microscopyfunction.
 28. The substrate inspection apparatus in accordance withclaim 26, in which said scanning electron microscopy function is used ina mark detection for a registration in a wafer processing process, andsaid image projecting function is used in a subsequent pattern defectinspection.
 29. The substrate inspection apparatus in accordance withclaim 1, in which said image processing system captures each of imagesfor a plurality of regions to be inspected which have been displaced onefrom another while being superimposed partially one on another, and saidimage processing system comprises: a storage means for storing areference image; and a defect determination means for determining thedefect in said substrate by comparing the images of said plurality ofregions to be inspected which have been captured by said imageprocessing system with said reference image stored in said storagemeans.
 30. The substrate inspection apparatus in accordance with claim29, in which said beam source radiates the electron beam onto each ofsaid plurality of regions to be inspected, and said detecting systemdetects the secondary electron beam emitted from each of said pluralityof regions to be inspected.
 31. The substrate inspection apparatus inaccordance with claim 30, further comprising a deflecting means fordeflecting said electron beam and thereby irradiating sequentially saidelectron beam onto said plurality of regions to be inspected.
 32. Adevice manufacturing method in which a substrate is subjected in thecourse of process or after having been processed to an inspection fordetecting any defects thereon by using the substrate inspectionapparatus as defined in any one of claims 1 to
 31. 33. A substrateinspection method, comprising the steps of: a. carrying a substrate tobe inspected into an inspection chamber; b. maintaining a vacuum in saidinspection chamber; c. isolating said inspection chamber from avibration; d. successively moving said substrate with at least onedegree of freedom; e. irradiating an electron beam having a specifiedwidth; f. helping said electron beam reach to a surface of saidsubstrate via a primary electron optical system; g. trapping secondaryelectrons emitted from said substrate and guiding them to a detectingsystem via a secondary electron optical system; h. forming a secondaryelectron image in an image processing system based on a detection signalof the secondary electron beam obtained from said detecting system; i.detecting a defective location on said substrate based on the secondaryelectron image formed by said image processing system; j. indicatingand/or storing the detected defective location on said substrate; and k.taking said substrate having been completely inspected out of saidinspection chamber.
 34. A pattern inspection apparatus comprising anelectron beam irradiating optical system for forming an electron beamemitted from an electron gun into a rectangular shape and irradiatingthe formed electron beam onto a sample surface to be inspected, and animage projecting optical system for forming a secondary emission beamemitted from said sample into an image on a detector, thereby saidapparatus having a function for image projecting said image of thesecondary emission beam, wherein said apparatus further has a functionfor forming a narrower electron beam by said electron beam irradiatingoptical system, irradiating said narrower electron beam onto andscanning therewith the sample surface, and detecting the secondaryemission beam emitted from said sample.
 35. A pattern inspectionapparatus having: a function for forming an electron beam emitted froman electron gun into a rectangular shape, irradiating the formedelectron beam onto a sample surface to be inspected, and forming asecondary emission beam emitted from said sample into an image on adetector so as to perform an image projection; and a function forforming a narrower electron beam by the electron beam irradiatingoptical system, irradiating said narrower electron beam onto andscanning therewith the sample surface, and detecting the secondaryemission beam emitted from said sample, wherein during a single samplebeing inspected, the function can be switched appropriately from eitherone of the function of the image projection or the function of detectingthe secondary emission beam to the other, in dependence of a conditionof said sample.
 36. A pattern inspection method comprising the steps of:preparing a pattern inspection apparatus, said apparatus having: afunction for forming an electron beam emitted from an electron gun intoa rectangular shape, irradiating the formed electron beam onto a samplesurface to be inspected, and forming a secondary emission beam emittedfrom said sample into an image on a detector so as to perform an imageprojection; and a function as a scanning electron microscope for forminga narrower electron beam by an electron beam irradiating optical system,irradiating said narrower electron beam onto and scanning therewith thesample surface, and detecting the secondary emission beam emitted fromsaid sample; and on the same substrate, performing a pattern inspectionfor a hardly charged sample area by using said function of the imageprojection and performing the pattern inspection for an easily chargedsample area by using said function as the scanning electron microscope.37. A pattern inspection method comprising the steps of: preparing apattern inspection apparatus, said apparatus having: a function forforming an electron beam emitted from an electron gun into a rectangularshape, irradiating the formed electron beam onto a sample surface to beinspected, and forming a secondary emission beam emitted from saidsample into an image on a detector so as to perform an image projection;and a function as a scanning electron microscope for forming a diameterof said rectangular electron beam, irradiating the electron beam havingthe formed diameter onto and scanning therewith the sample surface, anddetecting the secondary emission beam emitted from said sample; andusing said function as the scanning electron microscope in a markdetection for a registration in a wafer processing process and usingsaid function of the image projection in a subsequent pattern defectinspection.
 38. A device manufacturing method in which a pattern of awafer in the course of process is inspected by using a patterninspection apparatus as defined in claim 34 or
 35. 39. A defectinspection apparatus for inspecting a sample for any defect thereon byfirstly irradiating an electron beam in a rectangular or ellipticalshape onto a sample and secondarily detecting secondary electronsemitted from the sample, said apparatus comprising: an MCP foramplifying said secondary electrons; a fluorescent screen for convertingsaid amplified secondary electrons into an optical signal; and a CCDcamera or a line sensor for taking out said optical signal as an imagedata, wherein a voltage applied to said MCP is controlled in associationwith a change in an amplification factor of the MCP inn order todetermine an optimal amount of exposure for the image containing saiddefect.
 40. A defect inspection apparatus for inspecting a sample forany defect thereon by firstly irradiating an electron beam in arectangular or elliptical shape onto a sample and secondarily detectingsecondary electrons emitted from the sample, said apparatus comprising:an MCP for amplifying said secondary electrons; a fluorescent screen forconverting said amplified secondary electrons into an optical signal;and a CCD camera or a line sensor for taking out said optical signal asan image data, wherein an emission current of said electron beam iscontrolled in association with a change in an amplification factor ofthe MCP in order to determine an optimal amount of exposure for theimage containing said defect.
 41. The defect inspection apparatus inaccordance with claim 40, in which said voltage applied to the MCP isdetermined by referring to a current MCP applied voltage MCP gain curve.42. The defect inspection apparatus in accordance with any one of claims39 to 41, in which said MCP applied voltage or said emission current ofthe beam is controlled in association with a change in a magnificationof projection of the electron beam or a line rate of said line sensor.43. The device manufacturing method in which a wafer in the course ofprocess is evaluated by using a defect inspection apparatus as definedin any one of claims 39 to
 42. 44. A feed-through unit incorporated in adetector of an electron beam apparatus, said feed-through unitcomprising: a feed-through section made of electrical insulatingmaterial; at least one electricity introduction pin fixedly attached tosaid feed-through section; and a connecting wiring for connecting saidat least one electricity introduction pin with a functional element,wherein said functional element includes a sensor, and both a pressureand a kind of gas in an inside of said feed-through section aredifferent from those of an outside thereof, respectively.
 45. Thefeed-through unit in accordance with claim 44, in which said functionalelement is arranged on an inner surface of said feed-through section andsaid functional element includes a CCD or a TDI sensor.
 46. Thefeed-through unit in accordance with claim 44 or 45, in which a wiringis formed in a net-like configuration on a surface of said feed-throughsection.
 47. The feed-through unit in accordance with any one of claims44 to 46, further comprising a metal flange.
 48. The feed-through unitin accordance with any one of claims 44 to 47, in which said electricityintroduction pin transmits a signal with frequency of not less than 10MHz.
 49. A semiconductor device manufacturing method in which thefeed-through unit as defined in any one of claims 44 to 48 is applied toa defect inspection for a semiconductor device in the course of processor after having been processed.
 50. An electron beam apparatus forfocusing a primary electron beam to scan a sample and detecting asecondary electron beam from said sample, said apparatus having beendesigned so as to form a decelerating electric field between the sampleand an objective lens, said apparatus comprising: a detector fordetecting a discharge or a precursory phenomenon of the dischargebetween the sample and the objective lens and then generating a signal;and a means for receiving said signal from said detector to obtain acondition for inhibiting any discharge from occurring.
 51. The electronbeam apparatus in accordance with claim 50, in which said detector is aPMT for detecting a light occurring in said discharge or said precursoryphenomenon of the discharge, or a sample ampere meter for detecting anirregular current occurring in said discharge or said precursoryphenomenon of the discharge.
 52. The electron beam apparatus inaccordance with claim 50 or 51, in which said means for obtaining acondition for prohibiting any discharge from occurring is a means forreceiving said signal from said detector and then controlling a voltageof said decelerating electric field or an amount of said primaryelectron beam so as to Inhibit the discharge from occurring.
 53. Theelectron beam apparatus in accordance with any one of claims 50 to 52,in which said detection of said discharge or said precursory phenomenonof the discharge is performed with respect to a part of the region inthe sample that would not be used as a finished product.
 54. A devicemanufacturing method in which a wafer in the course of process or afterhaving been processed is evaluated by using the electron beam apparatusas defined in any one of claims 50 to
 53. 55. An electron beam apparatusincluding a plurality of electron optical systems arranged in parallel,each of said electron optical systems having been configured so as toform a primary electron beam into an image on a sample and to form asecondary electron beam emitted from said sample into an image on adetecting means, said apparatus comprising: a low-pass filter, whereinsaid detecting means outputs a detection signal of the secondaryelectron beam to said low-pas filter.
 56. The electron beam apparatus inaccordance with claim 55 in which said low-pass filter can make acut-off frequency variable and changes the cut-off frequency independence on the sample.
 57. The electron beam apparatus in accordancewith claim 55 or 56, further comprising a lens including a plurality ofelectrodes made of insulating material with a metal coating appliedselectively onto surfaces thereof.
 58. The electron beam apparatus inaccordance with claim 57, in which said plurality of electrodes is madeof a single insulating material.
 59. A device manufacturing method inwhich a wafer in the course of process or a finished wafer is evaluatedby using an electron beam apparatus as defined in any one of claims 55to
 58. 60. A defect inspection apparatus for inspecting a sample for anydefect by irradiating the sample with an primary electron beam from anelectron beam source equipped with a Wehnelt electrode and thendetecting a secondary electron beam emitted from said sample, whereinsaid apparatus further comprises a control section for controlling avoltage applied to said Wehnelt electrode with time so that an emissioncurrent flowing to said electron beam source can be maintained at aconstant level.
 61. The defect inspection apparatus in accordance withclaim 60, in which said electron beam source comprises an electron gunhaving a cathode made of LaB₆.
 62. The defect inspection apparatus inaccordance with claim 61, in which a flat <100> mono-crystallineorientation having a diameter of not less than 100 microns is arrangedin a tip portion of said cathode.
 63. The device manufacturing method inwhich a semiconductor device in the course of process is evaluated byusing a defect inspection apparatus as defined in any one of claims 60to
 62. 64. An evaluation apparatus disposed in the vicinity of at leastone processing unit for manufacturing a semiconductor device so as toevaluate a resultant condition of a wafer after having been processed bysaid processing unit, said apparatus comprising: an evaluation conditionsetting system for setting an evaluation condition such that theresultant condition of a single wafer can be evaluated within aprocessing time per wafer by the processing unit.
 65. The evaluationapparatus in accordance with claim 64, said evaluation apparatus furthercomprising: an electron gun for emitting an electron beam; a lens systemhaving an electrostatic lens made of insulating material with a metalcoating applied onto a surface thereof and a deflector; a secondaryelectron beam detecting system; and an image forming circuit, wherein animage data is formed by scanning a wafer surface and then detecting thesecondary electron beam.
 66. The evaluation apparatus in accordance withany one of claims 64 or 65, in which said evaluation apparatus comprisesa plurality of electron optical columns each including an electron gunfor emitting an electron beam, a lens system and a deflector, and asecondary electron beam detector, wherein an image data is formed byscanning the wafer surface with a plurality of electron beams and thendetecting the secondary electron beam.
 67. An evaluation apparatus forevaluating a resultant condition of a processed semiconductor device,said apparatus comprising: an evaluation condition setting system forsetting an evaluation condition such that the resultant condition of onelot can be evaluated within a processing time per lot by the processingunit, wherein said evaluation apparatus further comprises: an electrongun for emitting an electron beam; a lens system having an electrostaticlens made of insulating material with a metal coating applied onto asurface thereof and a deflector; a secondary electron beam detectingsystem; and an image forming circuit, wherein an image data is formed byscanning a wafer surface and then detecting the secondary electron beam.68. A semiconductor device manufacturing method comprising a step ofevaluating a wafer in the course of process or after having beenprocessed by using an evaluation apparatus as defined in any one ofclaims 64 to
 67. 69. An electron beam apparatus for evaluating a sampleby irradiating a primary electron beam onto a sample while scanning saidsample with a predetermined scanning width and then detecting secondaryelectrons emitted from said sample, wherein after having scanned acertain region on the sample with said predetermined scanning width, theapparatus scans another region adjacent to said certain region by way ofa movement of a stage, wherein an amount of said movement of the stageis greater than said predetermined scanning width, so that the samplecan be evaluated for a larger region by repeating these steps.
 70. Anelectron beam apparatus for evaluating a sample by irradiating a primaryelectron beam onto a sample having a pattern of a minimum line width “d”while scanning said sample with a predetermined scanning width and thendetecting secondary electrons emitted from said sample, wherein if abeam diameter of the primary electron beam is denoted by “D”, then0.55≦D/d≦1.0.
 71. An electron beam apparatus for evaluating a sample byirradiating a primary electron beam onto a sample having a pattern of aminimum line width “d” while scanning said sample with a predeterminedscanning width and then detecting secondary electrons emitted from saidsample, wherein a beam diameter “D” of the primary electron beam isselected such that a modulation transfer function MTF of a signal at atime when the primary electron beam has observed a cycle pattern havinga pitch equivalent to a doubled minimum line width “d” should be0.42≦MTF≦0.8.
 72. An electron beam apparatus for evaluating a sample byirradiating a primary electron beam onto a sample having a gate oxideand then detecting secondary electrons emitted from said sample, whereinassuming that: a time period necessary for evaluating a unit area isdenoted by “t”; an amount of irradiation or dose per unit area isdenoted by “C” (Coulomb/cm²); a beam current of the primary electronbeam is denoted by “I_(p)”; and a modulation transfer function of asignal at a time when the primary electron beam has observed a cyclepattern having a pitch equivalent to a doubled minimum line width “d” isdenoted by MTF, then the beam diameter of the primary electron beam isselected such that 1/(C·t) or (MTF)⁴I_(p) can be maximized.
 73. A devicemanufacturing method in which a wafer in the course of process isevaluated by using an electron beam apparatus as defined in any one ofclaims 69 to
 72. 74. An evaluation method using an electron beam forevaluating a sample by irradiating a primary electron beam onto a sampleand then detecting a secondary electron beam emitted from said sample bythe irradiation of the primary electron beam thereon, wherein theevaluation is performed only with respect to a small number of chipsamong a large number of chips formed in a single sample.
 75. Theevaluation method using an electron beam in accordance with claim 74,wherein the number of said small number of chips is equivalent to thenumber of electron optical columns for forming the electron beam usedfor the inspection.
 76. An evaluation apparatus using an electron beam,said apparatus being equipped with an electron beam apparatuscomprising: a primary optical system for irradiating a primary electronbeam onto a sample; a secondary optical system for delivering secondaryelectrons emitted from said sample by the irradiation of said primaryelectron beam; a detecting system for detecting the secondary electrons;and an electron optical column for accommodating said primary and saidsecondary optical systems, wherein said electron optical column has anelectrostatic lens including an electrode made of insulating materialwith a coating applied onto a surface thereof, and an electrostaticdeflector or an electrostatic astigmatic correcting lens.
 77. Theevaluation apparatus in accordance with claim 76, in which each of saidelectron optical columns forms a plurality of electron beams.
 78. Adevice manufacturing method in which a sample in the course of processor after having been processed is evaluated by using the evaluationmethod or the evaluation apparatus as defined in any one of claims 74 to77.